Hi ladies I have a question

Has anyone had to deal with a death in the family ?
My Dh's nanna passed away this weekend and the kids seem to be struggling .

She was a 100 yrs old and Hamish seems to be focusing on 100. If anything is brought up about it he mentions 100 , is anyone else 100? etc etc.
But of more concern to me is that he has been very very quiet this weekend and seems to have withdrawn. We had family get together and a few people mentioned how quiet he was. He has been like this for 2 days ... Should i start to worry