termites mulch beds
There is not alot you can do for termites in the soil around the structure as termites in the notheast are subteranean. The bigger question is has Terminix properly treated your customers home. The reality is an adequate termite service takes atl least 150 gallons termiticide (depending on size if home) which may last 5-10 years at best so any surface spraying you do with a labeled insecticide will degrade too quickly to make any difference. Besides why are the homeowners digging through you freshly laid mulch anyhow.