getting the deed in my sons name

My son and his wife divorced in Feb,23 2010 and in the divorce she gave up the rights to the property she walked out on him and left 2 minor children behind its been over a year and she only seen them once i the mother of the son paid the house off because it was ready to go into forclosure now there are refunds due and they wont turn them over to me or my son unless they do a quick deed sale but she wont sign it but does sighn the divorce papers where it says the husband gets the house what can we do to get her name off of the property also me and my husband had done a lot of repairs on the house since the divorce please help want my grandchildren to be kept in the house because she dont want the children ages 2 and 8 thank you pls help us