Select subcategories from category id using Ajax, keep getting error 500

Hi .. i have a the following

My View

@extends('app')
@section('page_title','Add New Stock')
@section('content')
<div class="col-md-12">
    <div class="card">
        <div class="card-header" data-background-color="green">
            <h4 class="title">Stock</h4>
            <p class="category">@yield('page_title')</p>
        </div>
        <div class="card-content">
            <!-- Button trigger modal -->
            <button class="btn btn-success" name="add" id="add" data-toggle="modal" data-target="#ModalAddStock">
              Add New Stock
            </button>
            <button class="btn btn-warning" name="update" id="update" data-toggle="modal" data-target="#myModalUpdate">
              Update Stock
            </button>
            <button class="btn btn-info" name="edit" id="edit" data-toggle="modal" data-target="#ModalEdit">
              Edit Stock
            </button>
        </div>
    </div>
</div>  
 <a href="#" id="try" data-link="{{ url('/test') }}">Try</a>
@endsection

@section('scripts')

<!--<script src="{{url('/')}}/assets/js/populate.js" type="text/javascript"></script>-->

<!-- Modal Core -->
<div class="modal fade" id="ModalAddStock" tabindex="-1" role="dialog" aria-labelledby="ModalAddStockLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
        <h4 class="modal-title" id="ModalAddStockLabel">Add New Stock</h4>
      </div>
      <div class="modal-body">
            <div class="row">
              <form role="form" method="post" action="{{url('/ajax/populate/subcategories')}}" id="form-create">
                <div class="col-md-6">
                    <div class="form-group label-floating">
                        <label class="control-label">Title</label>
                        <input type="text" name="title" required class="form-control" >
                    </div>
                </div>
                <div class="col-md-6">
                    <div class="form-group label-floating">
                        <label class="control-label">ID</label>
                        <input type="text" name="id" required class="form-control" >
                    </div>
                </div>
                <div class="col-md-6">
                    <div class="form-group label-floating">
                        <label class="control-label">Price</label>
                        <input type="text" name="price" required class="form-control" >
                    </div>
                </div>
                <div class="col-md-6">
                    <div class="form-group label-floating">
                        <label class="control-label">Quantity</label>
                        <input type="text" name="quantity" required class="form-control" >
                    </div>
                </div>
            </div>

            <div class="row">
                <div class="col-md-4">
                    <label class="control-label">Category</label>
                    <select class="form-control" id="category" required name="category">
                        @foreach($categories as $category)
                            <option value="{{$category->id}}">{{$category->title}}</option>
                        @endforeach
                    </select>
                </div>
                <div class="col-md-4">
                    <label class="control-label">Subcategory</label>
                    <select class="form-control" id="subcategory" required name="subcategory">
                        <option value="0">choose a category</option>
                    </select>
                </div>
                <div class="col-md-4">
                    <label class="control-label" >Brand</label>
                    <select class="form-control" required name="brand" id="brand">
                        @foreach($brands as $brand)
                            <option value="{{$brand->id}}">{{$brand->title}}</option>
                        @endforeach
                    </select>
                </div>
            </div>              
            <div class="clearfix"></div>
            <div id="response" name="response"></div>
            <input type="hidden" name="_token" value="{{ csrf_token() }}"/>  
      </div>
      <div class="modal-footer">
          <div id="loading" name="loading"></div>
        <button name="add_stock" id="add_stock" type="submit" class="btn btn-info btn-simple">Save</button>
      </div>
      </form>
    </div>
  </div>
</div>  

<script type="text/javascript">

$(document).ready(function()
  {
    $("#form-create").on('submit',function(e)
    {
      e.preventDefault();
        $.ajax({
              headers: {'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')},
              url: "{{url('/ajax/populate/subcategories')}}",
              type: 'POST',
              dataType: 'json',
              data: {},
              success: function (data, textStatus, xhr) {

                  console.log(data);
              },
              error: function (xhr, textStatus, errorThrown) {

                  console.log('PUT error.');
              }
          });
      });  
  });

</script>

@endsection

My Route

Route::post('ajax/populate/subcategories','AjaxController@populate_subcategories');

My Controller

<?php namespace App\Http\Controllers;

use App\Http\Requests;
use App\Http\Controllers\Controller;
use DB;

use Illuminate\Http\Request;

class AjaxController extends Controller {

    /**
     * Display a listing of the resource.
     *
     * @return Response
     */
    public function index()
    {
        //
    }

    /**
     * Show the form for creating a new resource.
     *
     * @return Response
     */
    public function populate_subcategories(Request $request)
    {
        if($request->ajax()){
            $states = DB::table('subcategories')->where('parent',$request->id_country)->pluck("title","id")->all();
            $data = view('ajax-select',compact('states'))->render();
            return response()->json(['options'=>$data]);
        }
    }

}

i have tried almost everything.. i still keep getting the same error 500 on change.. its driving me nuts! .. please help.. the thank you's will come later..