The VMAC PiHat has an onboard EEPROM. This is intended as part of the HAT (Hardware Attached on Top), specification.
The EEPROM on the VMAC PiHat is not configured and defaults to blank. It was intended for possible future use and maybe left off.
In a nutshell, the HAT EEPROM is connected to two dedicated and reserved pins on the GPIO 40 way header (namely ID_SD and ID_SC). The device is included to automatically configure and provide the board manufacturer information, GPIO setup and a ‘device tree‘ fragment.