Very sad situation and more common that we would like to believe. Other than being totally truthful with the new provider and that provider understanding that a bit more "hand holding" is needed there is nothing that will work besides time. The longer the new situtation seems better the more relaxed the mom will become. Also the older the child gets the more they will be able to tell about their day and that should help too.

I probably would ask permission of the new family to share their story with one of my families that had been in care the longest and then ask that mom to sort of act like a support system too for the family. There is only so much as the provider I can do because it is trust in my she would be trying to learn. Knowing that another family feels the situation is an ok one might help to take away some of the fear and guilt - spread it out so to speak.

She might also need a situation for a bit that is in a more regulated setting with several adults on site in a daycare centre. In theory the more people around there is more accountability. Not always but again if it puts her mind more at rest she may need to do that till she heals.