2 year old's great grandmother about to pass away. He is very close to her. How to explain to the child?

My wife's grandmother is 93 and was in good health until a few weeks ago. My son is 2 years and 3 months old, and we have gone to her house to visit every weekend since long before he was born. He gets excited to go to her house and even "calls" her with his toy telephone when we are at home. I just found out that my wife's grandma has very little time left. Likely just a couple days at most.Can anyone give any advice about how to handle it or explain it to him? My uncle just died and my son was at the wake for about an hour and he did great. He didn't even realize what was going on and he behaved well. He didn't know my uncle so there wasn't much to explain to him. This one will be different though. Any advice would be greatly appreciated. Thank you! via /r/Parenting http://ift.tt/2oFBLsa