Please be specific a little bit more on your question for best assistance. Is it an objection letter due to marriage/relationship gennuiness? OR is it an obejction letter due to residency obligation.?
If due to residency obligations then please provide them the flight return boarding cards, passport copy where it shows stamp, if your spouse is currently working a job letter will add best value to this, a credit card/bank statement shows the recent months transaction, a copy of lease/rent or mortgage is also helpfull. Any type of bill which has your spouse name and address on it will be also helpfull. All these will indicate that person is settled in Canada. Is your spouse a Canadian citizen OR Permanent Resident.?