The ordinary world is the world before the apocalypse happened when the wife/mother was still alive. The book flashes back to when the wife was alive and things seems better for the man and the boy back then. We also learn a lot about the man through the flashbacks.
Meeting the Mentor
The call to adventure is when the ma and the boy have to make the decision to leave the mom behind and begin their journey south in order to survive the winter.
Crossing the Threshold
The man's refusal of the call is when he is having a nightmare in the cave due t the fears that has about survival for himself and the boy.
Test, Allies, Enemies
The man does not really meet a mentor but the boy sort of acts, unspoken, as the man's mentor because he keeps the man going and trying to survive.
The man truly realizes how sinister the world has become and realizes what he must do which is to protect his son at all costs and help him as much as he can.
Some of the tests and enemies the man and boy face are the packs of cannibals that they need to hide from or fight off to survive.