Widows benefits can be obtained at a reduced rate as early as age 60, full benefits at full retirement. They can also be obtained as early as age 50 if you are deemed disabled under Social Securities regulations. Now if you are caring for a child of the deceased under the age of 16 you can collect at any age.
I should add, if you are applying for disabled widows benefits and are seeking a determination of disability by Social Security you may want to seek the advise of a Social Security attorney. Other benefits are awarded simply by meeting the age requirements.