Several things. First, they make special collars for deaf dogs that vibrate so the dog knows you are trying to get his attention. I don't know if it's a good option for an aging dog who is becoming deaf, but it may be something to discuss with your veterinarian.
Next, now would be a very good time to create a space for your dogs that is kid-free. If he's crated-trained, then make sure he gets some quiet time in his crate. Cordon him off when he's eating and sleeping so that the kids cannot disturb him and trigger a panicked response. Try to make sure that every single interaction between your dogs and children is supervised. Never leave your dog alone with any of your kids.
Finally, teach your children never to approach the dog when he's sleeping, eating, or not facing them. If possible, and I know this might drive you a little crazy, they may want to walk a little harder to create vibration in the floor to warn the dog he is being approached. You may want to initiate the interaction between children and dog by approaching the dog yourself to let him know you're there.
There are some good resources here:
Also, I want to emphasize that of paramount importance is safety. deaf and blind dogs cannot see the signals of other dogs, they can easily become disoriented and lost outside, and are prone to being struck by cars. Never leave your dog in a backyard where it can get through a fence. Never walk a deaf and blind dog off leash. Never leave him alone in the same area with another dog and never leave him alone with your kids. I strongly recommend crate training; it gives the dog a safe "den" where he can rest away from threats and retreat to when he needs comfort.