old/application/controllers/admin/Contact.php

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Contact extends MY_Controller
{

    public function __construct()
    {
        parent::__construct();
        $this->load->model('UserModel', '', TRUE);
    }

    public function index() {

        $this->load->view('admin/sidebar', ['title' => 'Kontakt-Nachrichten']);
        $this->load->view('admin/footer');
    }
}