You've got to LOVE that kind of determination.......even if she makes you nuts.
One of my friends has a mother with a similar M O, so last Christmas, when she started, he did as I suggested. He acted like he was in a panic and called 911 (faked it) and told her that she MUST be hospitalized because he was afraid she was having a heart attack or a stroke. He got his wife AND 3 adult children running around packing Grandma's things for the hospital. She snapped RIGHT out of it, and he says she was almost bearable the rest of her visit.
I like YOUR'S better, but thought you might want to file this idea for future reference. :)