Your mom doesn’t have ties to return. It is a job, income property etc. Volunteering is not a tie to return. Maybe try one parent only applying so tie to return is the spouse.
There have been a couple of such cases on this forum where parents' visa has been rejected. Like already mentioned above there is the risk of overstaying after the delivery. I would also recommend a 2-3 week itinerary max and about 10-15 CAD for this visit.
Your mom doesn’t have ties to return. It is a job, income property etc. Volunteering is not a tie to return. Maybe try one parent only applying so tie to return is the spouse.
If I apply for my father's visa now stating that my mother will not be accompanying him. However, they both travel together later, could it cause any issue? They both have properties in their names. Will property tie be sufficient?