When deciding whether a person who lived in your home, who you supported and who did not earn any money, is a dependent, you must apply a joint return test.
In most cases, you cannot list as a dependent someone who files a joint tax return with someone else (usually a spouse).
The only exception is when neither the person you claim to be a dependent nor their spouse has sufficient income to be taxed, but they have filed a return to receive a refund of withheld wages.