Your best efforts were enough until your mother's needs reached the level of clinical intervention. Would you be so down on yourself if the intervention included an iron supplement for anemia? I doubt it.

PLEASE treat yourself gently on the subject. Yes, you reached a point where you can't keep a close enough eye on your mother 24-7. It happens. But rather than risk your mother being hurt by accident, you did the smarter, more difficult thing, and settled her somewhere familiar with people who will treat her well without having to be on call every minute of every day. They take turns, and you could not do that at home.