Looks like there is a bug with modules not inheriting is-mobile classes even with proper user agent, it should behave like this in the next release,
http://take.ms/zgVQz
However, do take note that if you forcefully place the module in a very narrow container and expect it to be responsive on a desktop browser, it would not work.
EasySocial 2 uses true responsive results. In other words, responsive styles would kick in only when you use a proper mobile browser or alter the user agent on a desktop browser as you can see from my screen shot