I love it. There is two way feed back on the ethics of both the client and worker.Yeah Facebook market place, and kijiji would be a start. Maybe after checking after with the personal network. Referrals are the best.
How does you wife promote herself? She could always mention you are doing this to her clients if there is a fit.
There seems to be a market for keeping seniors in their homes. Cheaper than a seniors apartment and familiar surroundings. If they spend a few bucks on repairs and updates it's still less than a seniors home.