There is 10 years difference between M. M. (Mary M.) and S. J. (Sarah Jane) Tarbell listed below in the 1850 census. The birth year for Hannah appears to be about 10 years off. In the 1860 census Hannah, wife of John, is listed as age 39, b. 1821, which also co-insides with the birth year on her headstone. In 1850 she would have been 28 and would have been age 14 at the birth of S. G. Tarbell. John Tarbell must have been married once or twice before Hannah.

Five doors down from John Tarbell is the household of Charles Greenfield and wife Harriet age 29. Living with them is J. N. (John N.) Tarbell, age 9. In 1910 residing in the household of John N. Tarbell is Mary Irish age 71 and is listed as his sister. Checking the 1860 census Mary Irish is married to Henry Irish and is 22 years old. In 1880 she listed listed as Mary M. Irish, widow, age 39. She, undoubtedly, is the M. M. Tarbell.

1850 Washington, Erie Co., Pennsylvania
284, 288
Tarbell, John, age 39, Farmer, PA
" Hannah, age 38, NY(1812)
" S. G., Male, age 14, PA
" M. M., Female, age 13, PA (b. abt. 1837-1838)
" S. J., Female, age 3, PA
" J. W., Male, age 1, PA
" Jesse, Male, age 84, Old Gentleman, MA
289, 293
Greenfiled, Charles, age 30, NY
" Harriet, age 29, NY
" Nancy, age 57, NY
" M. M, Female, age 16, PA
Tarbell, J. N., age 9, PA
--
Home in 1860: Edinboro, Erie, Pennsylvania
John Tarble 52
Hanah Tarble 39
Sarah J Tarble 13
Jesse W Tarble 11
Wm R Tarble 6
--
Home in 1910: Washington, Erie, Pennsylvania, May 2
John N Tarbell 67
Rebecca C Tarbell 43
Harry N Tarbell 38
John R Tarbell 32
Mary Irish 71