Mother's diagnosis

Mother is 77 year old diabetic who had a heart attack 12/23/98.  she was on the diabetic medication of rezulin until January 99.  During some routine blood work it showed her liver enzymes as elevated and the doctor took her off the rezulin.  some months later when the numbers did not go down he sent us to a gastroenterologist.  The enzymes went down and up but they never leveled out.  In the fall she had  an MRI to rule out a bile duct obstruction.  This was negative.  In November for some reason the lab ran the full hepatitus (hepatitis) series.  This showed her with an active case of Hepatitus (hepatitis) C.  The doctor re ran the series and called me on the 23rd of December.  This confirmed the visus.  The doctor says due to her advanced age they will not do any treatment and besides nothing has been proven to work.  So I know that without a biopsy you can not tell how severe the liver damage.  What does this mean to her life expantancy?