I can assure you that the fact that the son died 3 days before Christmas has no bearing on their feelings this Christmas. The pain of the loss is too great and it wipes everything else out of their minds, even Christmas. Next year Christmas will be painful for them, and every Christmas in the future will be tainted with the loss of him.
Unfortunately so.
Unfortunately you cannot "assure" me of anything. I spent a Valentine's Day choosing a casket spray for my only child. So don't "assure" me what anyone's feelings are about losing a child on a day when the rest of the world is celebrating happiness.
Last night, I went to friends who are burying their son today. Yes, Christmas lights and wreathes, like the ones on the door of the funeral home, will now forever be associated with death for the family.