For an elderly person, just use iCloud for photos backup. It works incredibly well, and works through the native photos app, so it will totally eliminate the need to think about backing up unless it's offline all the time.
While I agree that iCloud is indeed great, it is more of a "sharing between devices" solution than a backup. If you delete a photo, it gets deleted on all your devices, and the only way to get it back is through iCloud.com.
What don't you like about that? It becomes the de facto storage for everything you can see. I don't really understand why you'd delete a photo that you want to keep?
