Hello,

Consider the possibility to make a sticky footer: Theme Settings > Footer.

If you do not like a sticky footer, you can create the footer in HTML block, insert accordion and set the visibility of the columns on different devices:
1. http://prntscr.com/j4fho7
2. http://prntscr.com/j4fio2

You can add any elements in to an accordion. In order to add HTML block into the footer, you can use HTML block widget

Best Regards