The settings for AOS within the browser should allow for you to set social sites to allow.
I couldn't find any such settings for the addon in firefox. I have Chrome on my laptop and will check it out there tomorrow.
Just to repeat some useful info, if you disable the browser plug-in, you still have Avast Web Shield protection. I use Web of Trust for firefiox, which will warn if I try to go to a questionable site, which I think is essentially what the Avast plug-in does, so I just disabled the Avast extension, still have Avast running otherwise and have Web of Trust to provide some proactive protection.