Bearbait, sounds like you have two dilemmas. One is your mother maybe needing some attention and she's 5 hrs away, and then your wife not being able to handle all the chores if you can't.
You don't mention other family members or children in the equation and that could add another dimension. Set down with whoever is involved and do some green light thinking, nothing right, nothing wrong, just ideas. Get a lot of ideas tossed out and then start to come up with the best or combine some of them.
Maybe move your mom closer, or to your home. Have someone in her community keep a close eye on her and report to you how she is doing. Let someone live with her in her home in return for the company and safety factor.
For yourself and wife, as your health dictates the feeling you need to move but your desire is to stay there, do the same thing. Look at all the possibilities you can dream up. Then discuss what you both think will be the best.
My wife and I took care of our neighbors for a few years. His wife passed away and a few years later needed help himself. They had no children. After we saw how that went, my wife and I put everything in a trust. That document forces you to think through the situation you bring up and lets you have peace of mind knowing the plan. If I'm gone she knows what realtor to call, and what auctioneer! She can sell anything or everything and do whatever she wants.
The plan, whatever it is, brings peace of mind.