People often put assets (such as money, houses, cars, etc.) into someone else's name in order to keep their own assets below a certain level so that they're eligible for Medicaid, nursing homes, or other such programs. I don't know if your mom's disability income has a limit on assets — I'm not at all sure that any disability income has an asset limit — but if she wants to buy a home and put it in someone else's name in order to keep receiving that income, then yes, it would be fraud.

Basically, if she would lose that income because she has money in the bank or a house in her name, then doing what she wants to do would be fraud.