Emma, can I just say that I am so so sorry to hear about your grandad. I lost my grandad in February. He had a type of cancer in his bone marrow. So I can imagine how you are feeling.
From what you are saying, I’m guessing it was quite sudden and that he wasn’t ill before he passed away.
It’s very hard to guess what caused it. I think the important thing is that if he wasn’t ill, he wasn’t in pain and that it was peaceful for him in the end.
It’s very early in the morning still so you should get more information later on today.
For now, you need to be there for your family. Help them in any way you can today. It’s going to be a hard day for everyone. I’m really sad for you, and I really hope that you are ok. I’m sure you have lots of people who can be there for you today and look after you.