i don't see any INCLUDE "MODEDEFS.BAS" and/or DEFINE OSC x so what about ...
SEROUT PORTC.6,0,["HELLO"]

NO?? what about now
SEROUT PORTC.6,4,["HELLO"]

Since this PIC have an internal USART, why you don't use it??? HSEROUT, HSERIN + an external inverter circuit like MAX232.