Soapy water is always a good preventative - 1/2tsp. to a quart spray bottle of water, and spray the whole plant including the undersides of the leaves and the soil surface before they bring it in the house. The rinse it off with plain water after a little while. If the white bugs show up after that, treat again the same way, and rinse the plant in the kitchen sink or the shower.
They should do this to all the plants that were outside for summer, before bringing them indoors.
