You have not mentioned what the source of your mom's income was. If she received more than $4400 --NOT counting Social Security---then you may be able to claim her as a qualified relative. If her income was more than $4400 from other sources -- like working, a pension, retirement accounts, etc.---she cannot be claimed as anyone else's dependent.
IRS interview to help determine who can be claimed:
https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent
https://ttlc.intuit.com/questions/3113432-who-can-i-claim-as-my-dependent
CREDIT FOR OTHER DEPENDENTS
https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
