/agree with Kialua.
Don't make yourself sick with worry over what to do. Call the hospital. Tell yourself that you will call the hospital to check on her, and you won't make any decisions on what to do until you've heard from the medical folks.
If they've put an IV in her, gotten her core temperature stable again and pumped some nutrients into her, she'll be on her way home in a few days (remember that hospitals and health insurance companies don't like paying for people to stay in hospital unless they really really need to be there).
If it appears that the problem is bigger than that, and possibly life threatening, the medical folks can tell you that and THEN you can decide whether you want to go see her again.
It sounds as if you don't have enough information to do more than call to check on her like you had been doing. The old tapes with the guilt and obligations and responsibilities? That is not your voice. As best as you can, try to find your inner voice and ask it what it thinks. It sounds, from your post, as if your own inner voice (the part that is truly you) doesn't want to go see her. That voice will give you much better advice than the old tapes.