Stage IV breast cancer. Got disability. Not enough to live on.

My mom was diagnosed with stage 4 breast cancer in March of 2016. She was given 2 years to live. In November, she was finally approved for disability and receives a monthly payment of $610. Her monthly house payment is unfortunately $650. She is struggling.

Because of the cancer, she can't work. She wouldn't have the energy or strength to do any job. She really wants to remain where she is at for the remainder of her life. It's where she's lived for 40+ years.

She's asked me if there is any other assistance that she can get from the government as she's falling behind.

I was researching from this site and found this:

"In some circumstances, you can receive both Supplemental Security Income (SSI) and Social Security Disability Insurance (SSDI) benefits at the same time. This is commonly referred to as “concurrent benefits”.

From some brief searches, it looks to me as if she could be eligible for both. She is definitely a low income case. She has no assets. No money in any bank account or anywhere. All she has is the house that she lives in and this $610/month income from disability. Could she be eligible for both? Why didn't the state tell her this or why didn't her social worker sign her up for both?

Unfortunately I just don't understand everything there is to know about SSI and SSDI so I'm writing here before I tell her any of this to see what might be able to help her. Thanks in advance.