If I claim mom as a dependent, can the IRS take my husband and my tax refund if we claim her?

This depends on how much of the SS the IRS has withheld this year. There are stringent rules for who is a dependent. A dependent has to live with you, receive at least half of their support from you, and not make more than $3650 a year. I would check with the IRS to see if the portion they garnished would still be counted as income. This is not an ordinary case.