This probate record seems to indicate pretty clearly to me that Elizabeth (Crossman) Luscombe of Taunton, wife of Francis Luscombe was still alive when her father wrote his will in 1736 (left side, next to third "item")
On the other hand, the Taunton VR show her death 16 Feb. 1733-4, age 49:
A land record shows her daughter Mary "Molley" who married Nathaniel Fuller (middle, right side):
And Molley's gravestone and the announcement of her death both show a birth year of about 1739 (and her husband was born about 1740).
So it seems to me the easiest resolution to this conflicting data is that Elizabeth (Crossman) Luscombe's gravestone transcription is incorrect -- she needs to have died later because of her father's will and also because it is highly unlikely she would have had daughter Mary at age 55.
Is there a way to confirm that her gravestone record is incorrect without travelling to Massachusetts?
Edit: The big sticking point here seems to be the age of Molley Fuller, who in the deed is noted as a "daughter" of Elisabeth Crossman.
Several newspapers ran the following text in November of 1825, e.g., Providence Patriot & Columbian Phenix of 9 November,
"Mrs. Mary Fuller, in the 87th year of her age, wife of the late Mr. Nathaniel Fuller -- leaving upwards of three hundred descendants, several of them of the fifth generation."
See also the Rhode Island Republican of 10 November and Rhode-Island American of 11 November and Newport Mercury of 12 November, Essex Register of 14 November, etc.
This is corroborated by the gravesite information at the RI Historical Cemetery Commission website (death year mis-transcribed though):
That same site shows husband Nathaniel is born ca. 1740, which is corroborated by a notice in the Rhode Island Republican of 17 June 1812 announcing the death at Providence of Mr. Nathaniel Fuller, age 72. Here's Nathaniel's profile:
In particular, the linked profile of his child Isaiah Fuller has an image of a death notice from which we can infer a birth year of about 1780. (That the listed children are theirs comes from the complicated probate record of their son Nathaniel Jr., which lists 52 heirs and from which I recreated the families of his eight brothers and sisters who had issue -- all had predeceased him.)