menus.php

<?php

if( is_page( 'page-slug-or-ID-here') ){
    wp_nav_menu( 'menu-id-here')
}elseif( is_page('another-slug'))  {
    wp_nav_menu( 'another-menu-id-here')
}


//Another solution is to register your menus with page slugs and then output a menu
global $post; //set the global $post variable
$slug = get_post( $post )->post_name; //set $slug to 'post_name' value irom the object

wp_nav_menu( $slug );