Survivor benefits for 46-year-old widow

Receipt of survivor benefits depends on your situation, but survivor benefits may be difficult unless you are caring for a surviving child who is younger than age 16 or disabled.

You may be eligible for reduced widow benefits as early as age 60. If you are disabled, benefits can begin as early as age 50.

See this link for details : http://www.ssa.gov/pubs/10084.html#2

I would consult Social Security directly for this.