One thing I can say is that if you have 3 in the cabin, most likely you and your spouse and your mother, you and your spouse probably would want to share the bed. The other sleeping spots are the couch that they convert into a bed, and a pulldown murphy bed. Neither would be suitable for an 81 year old in my opinion. The murphy bed is like the top of a bunk bed, she would have great difficulty climbing up to and the couch bed doesn't pull out like a typical pull out couch. They just take the cushions off the top and make it into a bed, and it is really small. My 13-year old daughter's feet were hanging off the end of it. Perhaps you can ask your TA for different sleeping arrangments. Otherwise, this category of a cabin is PLENTY spacious. We had 5 of us sleeping in there, and the only trouble we had was when we were all trying to get ready for dinner.