I did not see her in Findagrave, although Cyrus is in High St Cemetery. But maybe she had her cause of death listed in the not-online federal census pages which give the cause of death for people who have died the year BEFORE the census was taken. Or it could be in books such as those compiled by Dr. Samuel Beach Bradley, who was a physician in that area for many many years, and whose books and work are in the Rochester NY library. I checked his name in worldcat.org ad there are several libraries that hold his books. Familysearch also has them.
Cause of death might have come from records which exist in paper but are not online.