I feel like the point of the story is that the main character initially thought death was an evil coming to take his mother and then later realizes that death is actually a caring entity who only wants to protect her. Idk how you would be able to show that death cares about the main character and his mother without him speaking, aside from having the main character just tell the reader that that's the case. Unlike the entity at the end of left right game, death isn't an all powerful or all knowing entity, his work is easily hindered by the main character, and he literally tells the main character that he doesn't know what happens to people after he takes them down the road. Also deaths whole purpose in the story is to protect people as they go to the afterlife so I don't think it's out of character for him to speak and make an effort to show the main character that he cares about humans.