Thanks, for the responses.

What my letter stated that I need to bring to the nexus interview was the copy of the letter of conditional approval, and the passport (which I put in the application form as both evidence of citizenship and also of residency - the application form allowed a passport to be considered evidence of residency).

I can bring a copy of a utility bill, mortgage payment or bank statement.

The question is whether a driver's license or an OHIP card would be considered evidence of residency.