The correct option is C get over
The context refers to a person's state of mind/being after losing his job. "To get over" in option C indicates dealing with a problem and returning to one's usual state of being. This is correct as this phrasal verb implies that the subject will never be able to deal with losing his job and returning to normal.
"To get on with" something to carry on and continue with a task assigned.
"To get along with" someone is to be on good terms with them.
"To get off" is to leave work with permission as at the end of one's work shift.
Thus, option C is the correct answer.