Design the mobile menu in Divi Visual Builder, save it as a layout and then add it to the mobile menu from Divi Library. Just in a few clicks.
You can design the mobile menu layout entirely in Divi Visual Builder using all the available modules such as blurbs, text, contact form, opt-in module, as well as button and search modules, etc.
Or you can add only specific layouts/modules to the normal mobile menu above, below or both above and below the menu items. Divi Builder combined with the MMC plugin features will allow you to create truly unique and feature rich mobile menus.