FFF: Sleeping

My first thought is why would a couple get a babysitter who has never held a baby before to watch their baby?  The whole scenario is very strange.  The babysitter has no tasks at all except to be in the house.  Also, they had never talked to Harriet before asking her to babysit for them.  I would never leave my baby with someone I did not know very well beforehand. I was confused by the ending before reading it a couple more times.  However, I think the baby might have died and the mother is crazy because of it and is pretending like the baby is still alive and her husband is just playing along.