I am 61 and was diagnosed with Myelofibrosis in August 2001. This is a capricious condition and affects people differently. I have not found a doctor that is willing to discuss "how long do I have" yet. Has your mother given her doctor permission to discuss her condition with you? If so ask! A good doctor will answer any question to the best of his/her ability.
Blessings,
DayxDay