Can I just ask whether any of you have a health and welfare LPA? If so, the whole question is academic because that person can decide where she lives.
But if I was you I wouldn't insist on a particular home if the family member who is in a position to visit frequently says it is too far for him. You'd be giving him the perfect excuse not to visit at all. Yes, he might not visit much anyway wherever you put her, but you can't know that and it's a little presumptuous to say you would definitely travel those 52 miles all the time. You're not in his shoes, and you don't know the roads. If you think you can make each journey in under half an hour you assume he'll have a constant speed of about 55 miles an hour. That is only doable if all or most of that journey is on an empty motorway and not on country lanes or through a busy city, and that he is happy to travel by car every time. I live in London, and rarely is there a journey that takes under half an hour, but I am used to it, and after half an hour I am still only in another part of East London, and that is by public transport. To get out of London can be an utter nightmare. How far you travel on Swiss roads is irrelevant.
No offense to all your efforts in helping deal with the situation, but you are the one living in a different country, and no doubt there are resentments from your brother and his wife about this too, as you won't ever be able to get there quickly in an emergency situation.