My grandad pissed off a car full of drug dealers (serious) now what do I do?

They were parked outside the house in their car and he comes home drunk and starts shotuing racial profanities at them and threw a stone at their car, they drove off. Now I'm actually afraid of what they're going to do, they're drug dealers - they're not going to forget about it. Bricking the windows, breaking in, smashing the car, petrol bomb? idk what to do about this, I'm so scared.