How to list custom navigation menu with submenu?
You can use below function to render your custom menu your way

function _custom_menu_overview_tree_form($tree) {
  $output = '';
  foreach ($tree as $data) {
    $item = $data['link'];
    if ($item &amp;&amp; $item['hidden'] == 0) {
      if(strtolower($item['title']) == 'about us page condition'){
            $output .= '&lt;li class="right-nav"&gt;';
      }else{
            $output .= '&lt;li&gt;';
      }
      (0 == $item['plid']) ? ($class = 'parent') : ($class = 'child');

      if(isset($item['options']['attributes'])) {
        $attributes = array('attributes' =&gt; array_merge($item['options']['attributes'], array('class' =&gt; array($class))));
      } else {
        $attributes = array('attributes' =&gt; array('class' =&gt; array($class)));
      }

      $output .= l($item['title'], $item['href'], $attributes);

      if ($data['below']) {
        $output .= '&lt;ul class="sub-menu"&gt;' . _custom_menu_overview_tree_form($data['below']) . '&lt;/ul&gt;';
      }
      $output .= '&lt;/li&gt;';
    }
  }
  return $output;
}


And use below code in your html.tpl.php or where you want to render your menu

$menu_items = menu_tree_all_data('your menu name');
echo '&lt;ul class="foot-nav"&gt;' . _custom_menu_overview_tree_form($menu_items) . '&lt;/ul&gt;';


Please try this and let me know if any issues.