How do you refer to your mother in Canada? I would have thought it more likely that 'Mom' is used because of its proximity to the United States but here is exhibit A, Mr Geddy Lee, Canada born and raised clearly talking about his 'Mum.' He is from Toronto, for what it's worth.

https://www.youtube.com/watch?v=yz5UBnk-JOg

I guess it's province specific, right? I know people say things like 'Mum' is British and 'Mom' is American but that's not strictly the case. A lot of people in the UK call their mother 'Mum' (as I do) but if you're from the North of England or Wales you might call her 'Mam' (as my father did to his mum.) Or if you're from Northern Ireland maybe you call her 'Ma.' And apparently in Birmingham and the Black Country they even use 'Mom'. There are probably more variations. Having just explained that, I perhaps shouldn't be so surprised that there are some differences in another country.