Your query was posted so long ago that you may already have the answers. But I thought that I would go ahead and post what I have found:
Mary, wife of John Sweet the original immigrant, is popularly thought to be Mary Westcott. So far as I know, there is no evidence to support that surname. I notice that Robert Charles Anderson in "The Great Migration Begins" volume 3 page 1789 [?] does not give her a surname.
You are right, Mary and John Sweet did have three children including the daughter Maribah (spelled a number of ways in different records). She was NOT the daughter of Ezekial Holliman - as someone else has stated.
Ezekiel Holliman d. 17 Sep 1659 intestate and so the Town Council made a will for him. His widow, Mary Sweet, was executor and provision was made for her. But the remainder of the estate went to his two grandchildren, John and Rachel Warner, who were the children of his daughter, Priscilla, who had married John Warner.
The Town Council further made provision "for Susan Warner or other of ye children in England." I interpret this as meaning that Priscilla and John Warner had other children in addition to the John and Rachel who inherited from their grandfather.
In "The History of Warwick" by Oliver Payson Fuller, page 41, it is stated that Ezekiel Holliman also had a daughter, Mary, and possibily others. If that was so, I have no idea why the Town Council did not make provision for those other children. One possibility is that they may have died before their father and left no heirs.
Mary Sweet Holliman, widow of Ezekiel, left a will dated 31 Jul 1681 that seems to have left everything to her daughter, Renewed Garrardy. In records connected with the settlement of Ezekial's estate, she is referred to as "John Garrardy's wife whose name in her infancy was by information Meriba Sweet, afterwards called Renewed Holliman, then Renewed Garrardy".
Since Mary Sweet Holliman wrote her will on 31 Jul 1681, I assume that she died **after** that date. It could have been later that same day, or the next day, or several years later. I do not have a date of probate of her will.
What makes you believe that Mary Sweet Holliman moved to Massachusetts? I believe, but am not positive, that her will was in either Warwick or Providence. I will check to see if I can find that information. But I would expect that she died in Rhode Island.