Suggestion for someone whose mom passed away while he is in jail

I write to a guy in prison. He doesn’t have money or anyone to send him things so I started sending him books. His mom recently fell ill and was in the hospital and he thought she was recovering but then she passed away. He said he’s having a hard time with it. She was all he had and he didn’t get to see her. He said “sometimes I feel like I’m drowning and sometimes I feel like this is all a dream and my mom is still here”. It’s really sad. I was thinking maybe there is a book that could help. There are so many books about grief and coping but most of them are boring. Does anyone have a suggestion?
Thanks!