Distraction via Good Memories
If a child's fear is what materializes the "monster" then the lack of fear is what will defeat it (duh face palm answer down voted). Working with children in the past I have found that not reacting to what is causing them fear but staying calm and even talking about something off topic to be very helpful.
I was able to keep a child calm after he had fallen and his arm looked like a squiggly Tetris shape. He was crying and holding his arm being like a champion walking towards the building when my coworker saw his arm and started freaking out about calling an ambulance and .... after that the child was lost to his emotions and fear.
Breaking a child's focus on the danger / fear and giving a calm rock to feed off of will help dismantle the monster. (This is also dependent on a strong relationship between the child and the adult)
In terms of story having adults ask children to play, dance, bake a cake, ... anything to get the child to stop thinking on what is causing them fear. Every child who might be a target would have an adult tasked to keep the child's mind off of the monster.
Option 2: If the fear is just to intense then drugs. Just find a drug that prevents user from feeling fear. I heard that cocaine makes you feel god like maybe something similar or a completely made up one.