If she did not arrange for the writing and execution of a new will favorable to her, it is likely that she arranged the transfers of property before your father’s death. When people are dying, they often want to give things to those closest to them in their last days (sometimes because their memory of former days and relationships becomes vague). Deeds are granted for real property; the names of beneficiaries at death on financial accounts are changed; vehicles are transferred. The heirs after a death come to claim their shares and discover that the estate no longer has anything in it: jewelry, guns, boats, vehicles, cash, coins, stocks, and real property were transferred during the deceased’s last days. Sometimes a legal challenge can succeed, but you need to discuss the matter with an experienced attorney.