There are several shore excursions available for your mom...a one hour trolley tour when in Hamilton or a horse-drawn carriage ride in St. George. There are also several historic homes or government buildings on a tour in Hamilton, but of course, once you arrive you would leave the bus for short periods of walking.
I am on the Navigator now as I write this and my mom is not able to walk too far, either. She wasn't able to do excursions because it is so muggy here but she did find her suite on Deck Six to be convenient to the library, card room, dinner, etc.
Hair dryer in suite acceptable and had a diffuser.