If a step father inherits property from mother and he dies before transferring are the children of the mother next in line?

Mother dies, Stepfather wins court ruling that he gets the house, and other assets since the Mother's will disappeared and no one knows who the attorney was that she used to make the will. Stepfather dies a few months later before converting all of the assets from the Mother's name into his name. Niece of Stepfather is claiming she gets it all now since she is only beneficiary named in his will. Children of the mother wish to obtain the assets and house they grew up in. Attorney on her part threatens to have issue dismissed and charge the children his attorney fees.