How to help 3 year old girl stop peeing & pooping in her pants?

My granddaughter who is 3 has been peeing and pooping in her pants just about everyday several times a day. My son and his wife have been having marriage troubles, she had 2 affairs in 2 years. They don't fight in front of the kids but my Son moved out of the house. This is when the peeing and pooping really escalated. What can we do to help her? My son is so upset about this he moved back in and is sleeping on the couch.