Here are photos of 2 of the Presbytarian churches that exhisted in Verdun. Your grandmother probably attended one of these churches when she lived in Verdun in the 20s. One of the churches was at 503 - 5th ave. and another at the corner of Church and Ross streets. I have also included a map of Verdun. The address of 103 - third ave. where your grandmother lived in the 20s is between Wellington and LaSalle Blvd, on the east side (right).
I will be going to Verdun in a couple of weeks and can take a photo of that address and post it here if you wish.