Ask HN: Recommend a simple MMO for my retired mother?

Our family dog just died, leaving my retired mother alone at home with lots of time on her hands. She doesn't use Facebook (and doesn't have a lot of friends who do either), and she's never played video games before. I could make her a Facebook account, but I'm concerned Zynga-type games won't be fun if she doesn't have Facebook friends to play with.

She likes fantasy and science fiction, so I'm hoping to get her started on some kind of MMO as a way to interact with real people and keep herself busy. But something like WoW would be way too complicated and intimidating.

Surprisingly, simple Googling didn't turn up anything helpful.

Can anyone recommend a game that:

1) Is very, very simple to learn. 2) Is social, but more geared toward playing with strangers than existing friends.

Thanks!