I am 71 and have had MS for over 20 years. I have never been on a quilting cruise, but my husband and I have been on about 10 cruises, all but one since I was diagnosed. I have never had a problem except that the tour director wouldn't let me sign up to zip line in Panama or let me do the extensive walking tour on uneven ruins in Pompeii.
Ask for help when needed. Your fellow quilters will be more than happy to help you maneuver things. There is a place during pre-registration for your cruise to note any special needs you have- physically or dietary. I use a regular room as every bathroom I have been in has had grab bars near the toilet and in the shower/tub. I use a rolling walker and make good use of the seat to move things around including my tray at the buffet.
Have a wonderful time. I wish I were going with you!