This couple have 1 daughter that works and lives in a different city. They need help! They are alone, the husband wears Pampers. I deep cleaned their restroom after months and months of no one cleaning it. It was overwhelming. I feel bad, no parents should be left alone like this. Her husband stopped eating, lost his voice and can't hear. He sleeps 22 hours a day. I don't know what to do. I'm scared for them. Is he slowly shutting down? Please help me help them.
In fact, it will be better for them, for you, and for simply the making of progress if there is no sense of criticism in the air at all.
Consult the neighbour lady beforehand, and suggest that on her behalf you give your Area Agency on Aging a call to ask for advice and a needs assessment. Assuming she agrees, and if this is all taken as a matter of course there's no reason for her not to, then do that but also let the daughter know about it and ask the daughter if she would like to be copied in on developments.
The couple's needing help does not mean that the daughter must be first in line to provide it; and as they've been independent together for so long, I expect they would be the first to agree, don't you? So the key thing is to put them in touch with the people whose professional job is provide support services, and that's what I'd encourage them to accept.
If her parents are in their late 90s, the daughter might be in her late 70s. Maybe she has her own health issues to deal with. Maybe she can't go there and clean their bathrooms and they have refused to have 'strangers' help them out.
I think the advice to report the situation to APS is good advice. However, I would also try to get contact information for the daughter and express the same concerns to her that you express to APS. I would also reconsider how much physical help you offer to the couple. It's very kind of you but unless you intend to keep that up in the long run, you might just be reinforcing the elderly couple's belief that they are able to manage in their current situation.