My mother was denied widows benefits?

Do not understand why she was denied. Her and my father were married when he died. Says to qualify she had to meet requirements. Married to my dad under the laws of Chesapeake Va where he lived when he died. They were married in Norfolk thought marriage laws were state laws not city. You went through a legal ceremony which you thought resulted in a legal marriage and living together when he died. You have the same rights as a spouse to inherit from dad under the laws of Chesapeake Va. We live in North Carolina. Her and my dad separated but never divorced because of me. I do not understand why and i am pissed. Have filed appeal papers down at ss office and denied for same reason. If anyone can help i would be extremely grateful.