the reason she zaps to your side at the end is cuz she ran and used that transporter to the left of the elevator before the biggun comes after you, it's almost immeadiately after she zaps out that it appears and chases you D:
just keep searching for weapons until you get the Barret, BEST weapon in the game, shot through like 4 zombies at once, 3 headshots & 1 bodyshot. Also try to keep 7 survivors, it helps ;D
 "Vox Populi, Vox Dei(a werewolf thriller)"){kind=icon}
 "The Last Stand"){kind=icon}