I'm on SSDI, which is different from SSI, so it's important which type of Disability program she receives her payments. There are also many differences in the types of benefits she will qualify for.

She should qualify for a Housing Assistance program, which, by law, will take no more than 1/3 of your income. The problem is that oftentimes there is a waiting list to get on the program. It's important to find the right agency and get signed up ASAP.