I don't think there is much of anything you can plant that will not attract a bee at some point. The best thing for you to do is to keep an epi-pen available, and to train your staff how to use it and when. Last time I filled a prescription for one, it came with a dvd and pamphlet. This would be a basic to keep in the first aid kit, like at a front desk or some place handy.
A person may have never had a reaction previously to a bee, food, or other, but at some point can suddenly have a reaction. No past history does not mean it cannot happen.
