I feel you. I worry about something similar, though the details differ.
My thoughts are that I am happy to provide all kinds of support--helping to find a good realtor, to locate a cheap apartment in a safe but not glamorous area, to find and apply for assistance, etc. Money for people who have lived in a nicer house than I ever have? Not so much. If they can't see that as support, that's further indication that any money sent their way would just be wasted. Of course, getting DH on board is a touchy thing, and I have no idea what will happen if and when this comes to fruition.
There are more programs available to seniors than many are aware. That's always an option for them, and you can help with the time comes by assisting with research and applications.
Since these people are generally frugal (though I question that, if they are running up bills and declaring bankruptcy, unless there was some major medical bill or lawsuit or something), I might consider purchasing them a very modest home in a very modest neighborhood, and then making it clear that was it. You ask about that opening the door to others wanting handouts. You can very easily close that door with a "no", if it happens, but only if you and the wife are on the same page.
I'm also of the opinion that beggars can't be choosers. If they house they live in now is modest, maybe it makes sense to pay that off. If not, then if they want your help, they sell the house and use the proceeds, plus your contribution, for a simple place that keeps them clean and warm and safe, and has a few comforts, too.