Can Mom pay us rent while she's receiving Medicaid?

It's not clear from your question whether you are worried about applying for Medicaid for yourself or for your mother. In either case, eligibility depends on having low income and few assets other than a home the applicant lives in. The exact amount of income and assets varies a bit from state to state, and in some states, high medical bills can mean that someone might be eligible for Medicaid coverage even though their income would otherwise be a bit too high.

Your mother paying you room and board for living with you is perfectly legitimate (assuming the amount is reasonable). But the fact that it is a legitimate payment does not remove it from consideration by Medicaid.If Medicaid is considering your eligibility, the payments from your mother would be considered part of your income.If Medicaid is considering your mother, they will look at her total income when determining whether she is eligible, whether or not she spends some of it on room and board. However, her paying you for room and board might be to her advantage if she applies for Medicaid. That's because if she were receiving free room board from you, Medicaid might consider the value of that room and board as part of her "income," on top of the actual income she receives from other sources.