My mom has blood cancer and is in her final stage. What to expect? She is 47 years old. The doctor said she is immune to all medicine

Sick Mom. I'm sorry to hear about your mother. Without knowing the type of blood cancer your mom has i can't really tell you what to expect. I think you should talk about your concerns with your mom's doctor (after you get her permission first). Sometimes it's valuable to get a second opinion from a different doctor before you decide that nothing is helping her.
Comfort her. Probably the best thing to do in this case is to make her as comfortable as possible. Palliative therapy, like painkillers may help. Support groups might help also. It would be a good idea to talk about this to your/her doctor to get the best therapy for her.