This can be solved with the help of a hidden field input.Hope this will help somebody!
<?php
use yii\web\JsExpression;
$data = Company::find()
->select(['name as value', 'name as label','c_id as id'])
->asArray()
->all();
echo AutoComplete::widget([
'name' => 'Company',
'id' => 'ddd',
'clientOptions' => [
'source' => $data,
'autoFill'=>true,
'minLength'=>'4',
'select' => new JsExpression("function( event, ui ) {
$('#user-company').val(ui.item.id);
}")
],
]);
?>
<?= Html::activeHiddenInput($model, 'company')?>