Wife wishes to sell house but Foreigner Husband refuses to sign

The foreigner husband abandoned the wife and child and left the country. The wife could no longer pay the mortgage so she has found a buyer for the house before it will be foreclosed. She asked the husband to sign a wavier giving her the rights to sell the house. However he said he would rather the house goto foreclosure than her get any money for it. It seems he is worried if the wife makes money on it she will sue him for child support. Can the wife sell the house without the husband signature and transfer the title?? If she goes ahead with the sale can the husband show up months from now and contest the sale??