Jacob Farrar & Hannah Whitney, both of Concord, were married by Rev. E. Ripley, May 17, 1798.
The Whitney Research Group says that Hannah "likely ... was a widow, given her husband's age. Of whom she might have been a widow is a mystery." They obviously are aware of the Concord death record on p. 353, giving the death of "Hannah Farrar, Relict of ---", on 18 May 1839, but apparently ignored the age of death in the footnote that says "Widow of Jacob Farrar: aged 90. Gazette". Perhaps the Gazette article identifies her? Of course, she may have been a widow prior to marrying Jacob, but inspecting the americanancestors.org database of births for Hannah Whitney's around this time suggests the most likely candidate is Hannah Whitney, d/o George and Sarah Whitney of Holliston, b. 12 Apr 1748, so age 91. The others are either older, or from Connecticut. Of her, the Whitney Research Group only has guardian records through 1762, nothing more, and says she "may be" the one who m. 1800 Jesse Haven and d. 1842 (i.e, a slightly more extreme proposition than being the second wife of Jacob Farrar in 1798 and dying in 1839).