Aw, it's hard work when they get old and frail and have all these problems isn't it. I know you know she can't help it, but please do try to control your annoyance. She doesn't need the stress of feeling your disapproval on top of everything else.
Be cheerful, tell her it doesn't matter, and clean it up. Perhaps keep her in an area without rugs when you can't be there to take her out every hour, you know baby gate her in the kitchen, something like that? (make sure she has a comfy bed and her water of course.)
Or you could try training her to use a specific spot, in every room, and use puppy pads in those spots.
Welcome to pet lovers and please keep us posted on how she is doing.