Having posted this on several Facebook pages, I received a reply from Julie Cauvin from the Facebook Group Wenches in Trenches about Miss B. Gaviller. Julie says : "Her full name was Babette Olive Gaviller. She was born in England in 1892 and emigrated to Canada with her parents in 1898. She died in Collingwood, Simcoe, Ontario on 13th March 1970.
I think she had a sweetheart named Victor. One of her family members on Ancestry says on 13th June 1916, in the Canadian Convalescent Home for Officers, near Dieppe, France, Olive wrote “While we have been here, so many officers, both Canadians and English, have told me over and over again how splendid he (Victor) was at the front”. She never married.
No one is even remembering her on Find a Grave. I’ll put in a request for a picture of her grave. She’s buried at All Saints Anglican Cemetery, Collingwood, Ontario.
Babette served from 9/7/1915 until 4/3/1919."
Photo of Babette’s grave from Julie: Here you go, she's buried with her parents."
https://en.wikisource.org/wiki/Page:Brock_centenary_2nd_ed._1913.djvu/57