Unless Annah's FB is used as a TS support page (clearly it's not), then I don't see why she has to be okay with others talking about their transition 24/7. Obviously, there are people she prefer's not to know at this present moment and this friend could possibly out her. So, I totally understand where she's coming from.
Unfortunately, you can't control what each of us post on our own FB's so either unfriend her or tell her how you feel. Otherwise, you'll just have to deal with it. If she wants guidance from you, tell her you'll be more than happy to help her via e-mail or refer her to a TS support site like Susan's,
tsroadmap.com, etc.