In the death registry for Boston, 1859, Vol 131, p. 23, we find the listing for the death of Mahala M. Davis. The information listed matches what you have provided in your message. Cause of death is listed as "Inflammation of the lungs." Birthplace is listed as Newfield, Maine.

So far, I am unable to find an obituary. I hope someone else is able to do so.

MR