Dear Prudence, 
My mother, “Gladys” (78), is the most thoughtful, kind, funny, and sweetest person in the world. We’ve had our ups and downs, but as her one-and-only daughter, I can truly say she’s always had the best intentions for me and her grandchildren. Her husband, my stepfather, suffers from what I am assuming is dementia. He doesn’t speak much at all now—although he used to be quite the talker. My problem is that holding dinners turns into four or five-hour marathon entertainment sessions. Gladys just doesn’t seem to know when we’re all tapped out, exhausted, and wanting to wrap up a holiday visit. I feel guilty for giving clues, nodding off, etc. But what’s worse is she doesn’t seem to get the message. How do I end an evening without offending her?
—Totally Tired on Turkey Day