It would be better if you are able to get the PCC to be even,but and this is only a suggestion,you can extend City B duration to cover City C,provided you you haven't used City C address else where in any other visa application,and you have to remove that address from the History aswell.
Single PCC:I have had a bit of research on this Single PCC and turns out,If you commit crime in any part of Pakistan,eventually the record will be held at the two Police offices you have on your NIC card,and the Police station where you committed the crime,so one single PCC for one country is enough.
Multiple PCC: This is just an assumption(might be wrong),If couple of applicants have applied with multiple PCC from Pakistan,e.g ID card containing addresses of two different Districts,The Visa Officer is lead to believe,others should provide two PCC,if cities are different since 18th birthday.
To be Safe : Provide them with the PCC of City C,,since it is the most famous reason of rejection,Do your best to get this document.