How to grap table data to edit form in data dependancy selection inputs in Laravel 5.6?

working with Laravel 5.6 and I have table name vehicles and in this table data edit form have province, district and town data dependancy selection inputs like this,

<select name="provincename" id="provincename" class="form-control input dynamic" data-dependent="districtname" >
            <option value="">{!! $vehicles->provincename !!}</option>
            @foreach($town_list as $town)

            <option value=""></option>
            @endforeach
        </select>

 <div class="form-group row required">
            <label for="exampleFormControlSelect1" class="col-form-label col-md-3 col-lg-2">District</label>
            <div class="col-md-8">
           <select name="districtname" id="districtname" class="form-control input dynamic" data-dependent="townname" >
            <option value="">{!! $vehicles->districtname !!}</option>
</select> 

controller for this dependancy

 function fetch(Request $request)
    {
        $select = $request->get('select');
        $value = $request->get('value');
        $dependent = $request->get('dependent');
        $data = DB::table('towns')
               ->where($select,$value)
               ->groupBy($dependent)
               ->get();

               $output = '<option value="">Select '.ucfirst($dependent).'</option>';
               foreach ($data as $row) {
                $output .= '<option value="' .$row->$dependent. '">
                          '.$row->$dependent.'</option>';
               }
               echo $output;
    }

but when I click edit form provincename values select correctly in the selection input. but district name not selected acording to vehicle table values. how can I fix this problem? district data coming from towns table

via Chebli Mohamed