I really know nothing at all about the Seymour family, but the following record appears in the Williamsburg Town Clerk's annual report for 2002:

"September 29 [2002]: Merton Seymour, spouse of Mary E. O'Donnell; born September 9, 1924 in Westhampton, MA; died in Northampton, MA; buried in Center Cemetery, Westhampton, MA."

Merton Seymour lived in Haydenville, one of the two villages in the town of Williamsburg. His death may have occurred in Northampton because that's where the nearest hospital and nursing care facilities are located.

I suspect that a look around Westhampton's Center Cemetery would probably yield more information about the Seymour family -- as, of course, would a visit, call, or letter to the Westhampton Town Clerk's office. (In Massachusetts, vital records are kept by town and city clerks, not by county officials.) The main phone number at the Town Hall is 413-527-0463. Expect office hours to be limited -- Westhampton is a very small town.