I am not in a position to diagnose, but it sounds like OCD is a possibility...and yeah she would probably benefit from some treatment for it. I don't know a ton about that disorder but I imagine perhaps there is therapy and maybe medications since I've read people with OCD do experience anxiety related to the compulsions....like they keep doing the same thing because they have to, or they feel the world might end. But it could be something else...either way it might be good to suggest she talk to someone about it.

I mean as annoying as it might be for you to hear the same question over and over, its probably 10x as annoying for her having it stuck in her head like that, so she'd probably like some relief.