Since posting my original query I have found further information:
Sophie Maheux (spelled with the 'x') married Etienne Bourguignon in Ottawa in 1873. Both were originally from Quebec. They had several children born in Ottawa between 1874 and 1883. They apparently moved to Hull, Quebec sometime after that.However, there is no record of my grandfather, Oscar, born in Hull in 1898, although I have good reason to believe he was born in Quebec.