Cut out the drywall and get the bees from the inside. IF the comb is allowed to remain in the wall there could be far worse problems than the bees themselves.
Read on:
Extracting honey bees from buildings is considerably more difficult than collecting swarm clusters. When the colony is first established, only a few pounds of adult bees are present, but these bees rapidly build combs, collect honey, and begin to rear more bees. A well-established colony may have up to 100 pounds of honey, many pounds of adult and developing bees, and many beeswax combs. Removing such as nest is a challenge. The first step is to determine the exact location of the combs and size of the colony.
Although honey bees can be killed in place inside buildings by using pesticides that are labeled for killing bees inside of structures, this removal option often leads to undesirable consequences. (Note: These chemicals are available only to licensed pest control operators.) If the adult bees fall into a large pile, they may hold their body moisture and rot in place, producing a very bad odor. Liquid from the decomposing mass frequently penetrates the structure, leading to costly replacements.
If the colony is well established, there are further issues associated with killing the colony. Unattended brood can also rot and become very odorous. Unattended honey stores can absorb moisture and ferment, creating gas that causes the cappings holding honey in the cells to burst. Gravity will start moving the honey down attached surfaces until it encounters a horizontal impediment, such as a window frame, doorframe, firebreak, ceiling, or floor. Honey then seeps through the drywall, leading to large amounts of cleanup and expensive replacement. If pesticides were used to kill the bees, then the honey, wax and, dead bees are contaminated and must be handled as hazardous waste.
A better procedure than applying insecticides, especially if you have a beekeeper who is willing to help, may be to eliminate the bees without killing them. First the beekeeper will need to locate the nest by tapping the wall and listening for the hum of the colony. Some beekeepers rely on stethoscopes to find the edges of the nest. Others drill extremely small holes in the wall and insert a fine wire to find the periphery of the nest. To take honey bees and their combs from the nesting spot requires opening a fairly large hole in some portion of the building. That is best done by a professional contractor so that the hole can be easily closed after the bees are removed.
If the bees are to be saved, the beekeeper gently removes them and their combs. If the bees aren’t going to be saved, they can be removed from the void with a vacuum device such as a Shop-Vac. This process tends to stimulate the bees to release an alarm pheromone that smells like bananas and increases defensive behavior, so everyone nearby must be fully clothed in a bee suit. Many beekeepers have baffles and collection containers in their vacuum lines to try to protect and save the bees.
I'm sure there ar parishoners that can repair the wall free of charge.