Retro, condolences. Clearly, your grandmother meant a lot to your family. Since my kids have been born, their two great-grandfathers have past away. The most recent loss was right before the start of the holiday season. My 2nd grader asked questions about death. We answered his questions in the best possible manner that would not freak him out. I think what helped my wife and I, we didn't sit down and have deep conversation about it. If he asked a question while I was loading the dishwasher, we discussed it causally as I continued to load. Same if he asked while we were driving to the grocery store. I think that keeping it a casual conversation, made him analyze it as something that's a normal part of life. We also referenced movies like Coco. It's tough, though. There is no manual for this.
Good luck and know that your kids' questions will be just as good for you to heal as for them to understand life.