CNS Lymphoma--long-term cognitive losses

My mom (only 54 years old) has Primary Central Nervous System Lymphoma. She has undergone various chemo treatments for over three years. Now, there is no sign of the tumor, but she is suffering great losses due to the treatment. In the last 6 months my mom's congnitive abilities have drastically declined. She has completely lost her short-term memory, she can no longer express herself verbally (inability to recall words), she is easily agitated, and very depressed. All of these symptoms/reactions are devastating to my mom and our family. Clearly, she can no longer live on her own or care for herself. Right now, we are looking into nursing/assisted living care facilities.

Has anyone else suffered such huge losses due to chemo treatment? What did you do? Does any form of detox help? Also, does anyone have recommendations for nursing/assisted living facilities (for cancer survivors or individuals with severe brain impairments) in the Los Angeles and/or San Diego area? Thanks for your help.