I don't know if anyone else has raised this - but what about the family friend? I think by telling you she's absolved herself of the responsibility. Just a side thought....but hey, it's a small town.
You can screenshot her Facebook page before you raise the issue and show your father what it actually looked like if you are scared she may change it. Personally, I'd be talking to her directly and keep your father out of it. You can always frame it in a good light, tell her people are telling you about it and you want to check she's ok. Give her the knowledge that you wanted to talk to her about it as a courtesy as you'd hate to interfere in their marriage, but wanted to let her know people are talking.
When all is said and done, it is just Facebook. She could have changed the job or work location to protect herself from something else completely unrelated.
Just ask her!
