How to change value of $menu_class in ep_nav_menu?

There is no need to add any code for this. You can use the Screen Options on the menu admin end to achieve this. Please check the instructions below.

  • Login to the admin end of your wordpress site and navigate to Appearance => Menus section.

  • Click the down arrow against the menu item you need to have a different class for.

  • Then click on the Screen Options link on the top right section of your screen.

  • Check/click the CSS Classes option. Once checked, it will show an additional field CSS Classes (optional) below the menu item you had expanded earlier.

  • Now provide any custom class in the field and add the respective css code in your theme’s css file.

Note:

  • These steps are based on WordPress 3.8 version which may slightly vary if you are using a different version.