How to make a procedure that checks if a mob dies and if it does gives the player an item

I am trying to make a bounty hunter mod that when you kill a specific mob you get a random item, but I don't know how to see when that specific mob dies to the player.

This is what I got so far, also the reason it's on google docs is because idk how to put a picture on this so oh well.

 https://docs.google.com/document/d/1HnJ35FcobUPbEv6g8262f9AERyRIx9mocT2JSkaN6FQ/edit?usp=sharing