Hi Mark,
Sorry to hear this news, since you were so upbeat yesterday.
It's awful to hear your mum's in hospital, but you now know that she is in the best of care, and nursing staff will do all they can to help her. She may be not eating through depression, rather than anything physical?
Perhaps you could try ringing the hospital she has been taken to, and speaking to a member of staff directly. Explain the distance between yourselves, and ask that they contact you regularly, or inform them you'll be in touch regularly, to keep up to date with her progress.
Your step father may well be at a loss for how to explain things that are happening? Maybe he doesn't like to admit that he's not succeeding in getting her to eat or drink, some people take this as a reflection on themselves don't they?
However, the important thing is your mum, and I would be ringing twice maybe three times a day until you are satisfied that you know everything that's going on. Good luck honey, and try not to stress TOO much. Easier said than done, I know, but take some calming deep breathes and make some enquiries.
Keep us posted. Rooting for you.
Gill
xx