Yes, a child that has Social security income can be claimed so long as you provided more than half the support of the child.
For details on all the qualifications see A "Qualifying Child" :
In general, to be a taxpayer's qualifying child, a person must satisfy four tests:
I hope this helps for knowing the rules to claim a child with some income.
As you see, if she is "permanently and totally disabled at any time during the year" age does not matter for you to claim her as a Qualiyng child.
If not, you can see if she qualifies under Qualifying Relative rules:
There are four tests that must be met for a person to be your qualifying relative. The four tests are:
Not a qualifying child test,
Member of household or relationship test,
Gross income test, and
Unlike a qualifying child, a qualifying relative can be any age. There is no age test for a qualifying relative.
Social securty does not count toward her Gross income for this test.
See http://www.irs.gov/publications/p501/ar02.html#en_US_publink100041887 for more details.
It seems she can still qualify as a qualifying relative based on what you posted.
I hope this helps to clarify for you.