Jeffery Hui, along with Ranger Teresa Lutz, Corporal Marcus Christensen, and several other unidentified NCR rangers couldn't get out of Boulder City in time before it was blown up, so they held off Caesar's Legion as long as they could, either to buy time, or simply to kill as many Legion as possible. It is implied that Jeffery Hui and Cpl. Marcus Christensen were killed before the explosives went off, although the cause of death is unknown. Ranger Lutz implies in her holomessage that both Christensen and Hui should be posthumously awarded for their sacrifice and valor.
Jeffery Hui is mentioned in Fallout: New Vegas only.