Hi Judy, thanks for using Ask Extension.

Baldfaced hornets do not fall under the genus Vespa  (hornets) but under the genus  Dolichovespula which is a genus that covers arial yellowjackets.  They are an interesting bunch and for the most part will leave you alone unless they feel a threat, especially to the nest.  They do a lot of insect control and therefore considered beneficials.  They will die after a good freeze in the fall and will not reuse the nest. If you feel comfortable in leaving the nest where it is, that would be good. The fact that they are in the compost bin may indicate that they are either just visiting the compost, or they may be another type of pest.  The baldfaced hornet builds its nests usually in trees and shrubs and are not known to be in the ground or enclosed spaces (there can always be exceptions).  Note that baldfaced hornets have black and white markings, whereas yellowjackets have yellow and black markings.  Yellow jackets will build nest in the ground or other enclosed spaces,

Check out the following links:

Vespidae: Dolichovespula maculata - Dolichovespula maculata - BugGuide.Net

Are Baldfaced Hornets Friends or Foes? – Maryland Grows

Bald-faced Hornets | Yard and Garden

Insectsthatlooklikesbees-SmartGardeningWEB.pdf

I hope this helps.