HD44780 in 4bit mode connected to only ONE PORT on PIC
There is two methods you can use:


Address individual pins.  In XC8 you have such variables as LATBbits.LATB3 which you can set to 1 or 0 to turn an individual pin on or off.
Use bitwise operators and masks.  You can "or" and "and" bits together to turn chunks of a port on or off, such as LATB &amp;= 0xF0 will turn off the lower 4 bits.  LATB |= 0x03 will then turn the lowest two bits on without changing any other bits.