Hi there Colin, if you are still looking for this info, I do have information on a Mary Ann Jarvis that married a Simmons, he was my grandfather James Edward Simmons.
However, she is buried in Barachois Brook with my grandfathers family, not nearby Shallop Cove. (My mom actually attended her funeral in 1944.
Also, this person was née Penney, and Jarvis was her married name from her first marriage.
If this is your person, shoot me a note and I can give you more info as well as a photo of her grave, which is largely unmarked.
Carol Dimond