Yup, that's a hornet alright. Poor bee's get a very bad rap! As well as the onion that Hazel recommends, we use parsley on bee stings (rub it on the sting area once the stinger is removed). I've also heard you can use a penny or a banana peel, but only have experience with onion and parsley. We have a large parsley plant near the bee hives just to be on the safe side.
If you can locate the hornet nest you can have it removed by professionals or you can try using the commercial sprays - just be sure you read the instructions very carefully. I recently had to spray out a wasp next and I bought a foaming spray that worked well. I have 400,000 bee's in my yard and go figure Halo gets stung by a wasp!!