In your middleware, you start by setting $student equal to the current user. Next, in your if statement you use $student (which is a User object) and call the users() relationship on it which can not happen, because users() is a relationship of the Student model (not the User model, which is what you currently have $student equal to).
Based on what it looks like you are doing is, you want to see if the currently logged in user is an active user, right?
If that is the case, you can get rid of the whole $student = Auth::user() thing altogether. Just call Auth::user()->active == 1 in your if statement and you should be good to go.
public function handle($request, Closure $next)
{
if (Auth::user()->active == 1) {
return $next($request);
}else{
flash('Sorry! You Do not have permission.', 'danger');
return redirect('/oops');
}
}