Do you pay for over half of her support? Did she have less than $4300 of income --not counting Social Security?
Better make sure you can claim her as a dependent because if you get it wrong she gets NO stimulus money--dependents cannot receive stimulus checks. (And you do not get stimulus money for claiming her)
You might be able to get the $500 credit for other dependents if you can claim your mom.
CREDIT FOR OTHER DEPENDENTS