How to find which one is master/slave? - PIC
The EEPROM is the slave.

In the On Semi 24C256 datasheet, for example, it says


  The CAT24C26 acts as a Slave device.


However it should be obvious that this is the case, because the EEPROM has no idea what I2C address the PIC is using, nor which storage address should be read or written, until it is told, and the master is responsible for providing this information.

Also, under I2C, only the slave has an address. Since the EEPROM has an address (often even called a "slave address") it is clear the EEPROM acts as the I2C slave.