I'm so lost... I don't understand anything anymore

(if the death it's not staged)
The grandma basically "accidentally" killed sangwoo in her attempt to make him shut up, they gave bum his ashes and, since the granny told him that sangwoo was calling for him and that if he had courage that day he would have been able to see him one last time, he has gone even more crazy.
Again, though, if it is not a staged death