My mother in-law is getting insistent about going home. What do I do?

Some people make up delays. "You can't go home quite yet. They aren't done with the new sewer line in the road." This depends on the person's short term memory, of course, and their sense of time passing.

Does she have dementia? This is normal behavior. And most likely will not stop. Try telling her that they are hoping to help her remember things better. And the doc will make the decision when she will go home.