Assuming that she would be filing as Single, if her total gross income was less than $13,850 she would not need to file a tax return. However to get a tax refund of the taxes withheld she should file a tax return.
Also, if she received Social Security income, some of the SS income may be taxable. You should complete a tax return for her to see the actual numbers and see if she is required to file.
Up to 85% of Social Security Retirement/Disability/Survivors benefits becomes taxable when all your other income plus 1/2 your social security reaches:
- Married Filing Jointly - $32,000
- Single or Head of Household - $25,000
- Married Filing Separately - 0