I suggest you review the IRS site about dependents
https://www.irs.gov/credits-deductions/individuals/dependents
This allows you to read about the qualifications needed, or it has a link to walk you through a series of questions to determine if she qualifies as a dependent.
Remember that if you claim her as a dependent and she files her own return, she must check the box stating she can be claimed as a dependent on someone else's return.
