It really seems to be a very cancer-compatible story, but if her doctor says it's not, then we need to believe it's true. You as a family can only enjoy the few moments you still have with her, she is 87 years old and in front of this clinical situation it is difficult for her to resist for a long time, there is always to have faith and hope, she is hospitalized and probably well accompanied and treated with what you can do, there is no point in looking for illness or diagnosis at such a time (even if something is found, nothing will be done - it has no conditions for surgery or any other procedure or stronger medication). As a family, we have always believed that we were negligent, we always believed that we could have done something more. What you have been able to do you have done, now it is in the hand of medicine and God, it is up to you to give love and love, is what more she needs now.