Deep sleep mode consumption of PIC
I have found the answer, it was a mistake from my side. In the above code I have enabled the TRISC as output. That is the reason for .278 mA consumption shown there. If you configure TRISC as input, the consumption would end up with few tens of uA.

And if you do nothing other than deep sleep mode and remove the Port configuration code, the consumption would drop down to 80nA respectively.