What a superb ambition and I am sure that there is nothing to stand in her way. The Hermitage is large but easy to get around and full of everything I’m sure she expects to find there. The last time I went round was on a Celebrity Cruise’s tour and we had the early tour which meant that we were inside and looking at the art exhibits before many other people were even allowed in so I would recommend that you try for that. The ships nowadays are built to allow great access throughout and cabins for disabled people are well thought out. Go without any fears because you will have a great time....regards Id.