Add sidebars to navigation menu?

might it can help you for your query :

Basically I need a way to display widgets in menu, without using any
extra plugins.

place the code in your theme’s functions.php

<?php

register_sidebar( array(
    'name' => 'Page Menu',
    'id' => 'page-menu',
    'before_widget' => '<div id="page-nav">',
    'after_widget' => '</div>',
    'before_title' => false,
    'after_title' => false
) );

add_filter( 'wp_page_menu', 'my_page_menu' );

function my_page_menu( $menu ) {
    dynamic_sidebar( 'page-menu' );
}

?>

for reference Placing widget to menu and

http://justintadlock.com/archives/2009/04/15/how-to-widgetize-your-page-menu-in-wordpress