Had a cruise booked with my parents last March. 10 days before the cruise my dad went on dialysis and a 7 day cruise was no longer possible. My mother and I both reached out to our Carnival PVP we booked the cruise through. We were told we were SOL and nothing to be done. I called Carnival customer service - just the main line nothing special - and the rep who answered approved the refunds back to original forms of payment. I don't know if I got extremely lucky or they do this regularly. All three of us are platinum. They may have helped?
I hope your wife recovers quickly and you get this piece figured out without much hassle.