再婚后就不能拿前夫的了。如果现任丈夫死掉了，可以在前夫和现任之间选（与现任的婚姻长于9个月）

http://www.wiserwomen.org/index.php%3Fid%3D219%26page%3DSocial_Security_and_Divorce:_What_You_Need_to_Know

A divorced woman can receive Social Security benefits without filing any special papers at the time of divorce, and it doesn't matter if her ex-spouse has remarried.

A divorced woman must meet certain criteria to collect benefits based on her ex-spouse's work record:

• You must have been married for 10 years or longer.
• You must not be currently married. 

        - If you remarry, you generally cannot collect benefits on your former spouse's record unless your later marriage ends (whether by death, divorce or annulment).

        - If you re-married and your second spouse is deceased, you qualify to claim benefits from either your first spouse if that marriage lasted at least 10 years, or your second spouse as long as you were married at least 9 months before he died.

• You must be age 62 or older. 

        - If your ex is deceased, you can collect at age 60 as a surviving divorced spouse.

        - If your ex is deceased and you are disabled, you can collect at age 50.