If you are trying to create a new options in metaboxes oo in theme options to get all the wordpress menu list.Use the Below code.
<?php
$display_menus = get_terms( 'nav_menu' );
foreach($display_menus as $menu)
{
echo $menu->name;
}
?>
<?php
$display_menus = get_terms( 'nav_menu' );
foreach($display_menus as $menu)
{
echo $menu->name;
}
?>