Sorry. I did not test your template.
But maybe there are some additional information which could help you:
I actual started a similar thread in the german part of the forum.
The named thread from jacobi22 show how to prepare the output of the function show_menu2(). That concerns the html output.
For a responsive dropdown-menu in the template you need an css/js framework too. In the german thread fischstaebchenbrenn
er gave the tipp to have a look to folling template:http://WebsiteBaker.at/wb-templates/template-darkspace.html
which uses for the menu the css/js framework from:http://www.smartmenus.org/
Following link could be helpful too:http://cssmenumaker.com/
Other solutions and tipps to code it you will find in the web ...