This post at Possum's leads me to an update on my mother-in-law.

At last writing, she was feeble and incoherent. She underwent a full battery of tests that showed no evidence of a brain tumor or stroke that might account for her condition. Her doctor forbade her to take any more of the sleeping pills that she has used for whatever reason for many past years.

Now she seems to have recovered. We don't have a clue as to what caused such a sharp decline then. She's a little dotty, but from Lyman's reports and my observations that's been true for decades. So our family is off the skids for now.