According to the 1881-1901 censuses, Blanche stated that she was born in 1865.
There were gold rushes occurring throughout the 19th century, but there were other economic draws to Canada. For example, Montréal was one of the first cities to produce steel. As a railway wagon maker, her father would have found easy employment in that newly emergent railway market.
John's and Caroline's choice of this as a forename may have been influenced by their sojourn in Montréal (again, IF it was this couple in Montréal!!), but Blanche was a popular name in England during the 19th century.
Cheers,
Alison