Project Completion Plan for a job fair that was very successful on a military base that had a budget of 3000

Project Completion Plan for a job fair that was very successful on a military base that had a budget of 3000.00 The stakeholders were the Director of Army Community Services and the base commander. We didn't really need a budget, but included one just because of the assignment. 

A. End of Project Plan

B. Final Sign-off Plan

C. After Actions Report 

1. Pitfalls2. Assessing the Project Success or Failure

Which phase of the project management process is the most important in your opinion? Select one only one phase to defend.