Can the PHQ-2 be used for the MNCM Depression measure? What is the difference between the PHQ-2 and the PHQ-9? 

The PHQ 2 cannot be submitted for the MNCM Depression measure; you must use the PHQ-9. They both are from a long questionnaire (the PHQ), but the PHQ-2 is meant to be used as a screening tool whereas the PHQ-9 is meant to be used for assessing and monitoring depression severity. The PHQ-2 is actually just the first two questions of the PHQ-9.