Does she go to church? If so, find out where. Then write her a nice letter and tell her you're sorry for the apparent financial trouble she's having. Then tell her you plan to speak to someone at her church to see if they have any volunteers they can send over to help her with her future housecleaning. If she doesn't go to church, just name the one closest to her house where she's liable to know people. Who knows, maybe she'll be embarrassed enough to pay you just to keep you from "helping" her.