From the employee timetables in my collection, here is hopefully, the answers you seek:
Last year around passenger service to Provincetown was the timetable of April 25, 1937. The timetable of September 26, 1937 showed no passenger service. A new timetable came out on October 10, 1937 which showed one round trip six days
a week and this lasted through the remainder of 1937 and into 1938 with 7 day a week service during the summer until a
new timetable dated July 17, 1938 which showed no passenger service between Yarmouth and Provincetown.
After July 17, 1938 and it seemed strange to me that the trains would come off in the peak season there was no passenger
service until the summer of 1940 when the railroad ran one round trip a day six days a week from June 24, 1940 until
September 7, 1940.
From this it is very safe to say that the last regularly scheduled passenger train to Provincetown operated on September 7,
1940 although there was nearly a two year gap with no service.
As for freight operations to Provincetown:
The line showed in the timetable dated April 24, 1960 but in the timetable dated October 30, 1960 it had been cut back to
North Eastham so it was abandoned between North Eastham and Provincetown between April 24, 1960 and October 30, 1960.
This continued until the timetable of October 31, 1965 when it shows cut back to South Dennis so it was abandoned between
North Eastham and South Dennis during the period between April and October, 1965.
This was a fair amount of work and time but I have had an interest in the railroads of Cape Cod for many years.
Thankfully I had an opportunity to ride most of this territory except between South Dennis and Provincetown over the years.
Today I think it is a major shame that there is not passenger train service available between Boston and the Cape and
probably New York and the Cape as well.