What about something like a coach tour? Would he manage on and off the coaches - mind you, if he can't see well, he will not exactly be able to see the scenery, but he might enjoy the local history and stories the tour guides tell. At least most of the time he would be sitting down and could probably remain in the coach or in a cafe while your mum had a walk about during the stops. He would also get to stay in hotels and eat out and your Mum would probably find people to socialise with.
Hope you sort something out.