<div class="btn-group">
                <div class="col-md-10">
                             <select name="tipo" id="tipo" class=" form-control"  value="{{ old('tipo') }}"  required>
                                   @foreach($usuariosOpciones as $id => $usuario_ad)
                                   <option value="{{ $id }}">{{ $usuario_ad }}</option>
                                   @endforeach
                             </select>
              
                         <form action="{{action('UsuarioController@show', $usuario_ad)}}" method="post">
                               {{csrf_field()}}
                            <a class="btn btn-info" >Buscar</a>
                        </form>
                        
                   
                 </div>  
              </div>