Hi...So sorry for your loss. Will you get a necropsy done to find out what the cause was? If you are planning to, put him in the freezer til you can get him to the vet. The results will be a little off because of freezing him, but the vet should still be able to give you a diagnosis.
I am so happy for you that you could get one of his kids.
Make sure you totally bleach & soak, then wash & rinse, rinse, rinse, his tank before putting anyone in it. If you can rinse with a pressure hose it would be better. Do the same with all dishes and furniture.
Don't use any loose substrate for your dragons. No sand, chips, walnut shells, etc. A lot of us are now using textured ceramic or slate tiles. I got mine from a discount flooring store. They make clean up so much easier. Plus it doesn't harbor bacteria, fungus, parasites,etc. Until then just use paper towels.
Good luck
Patsy