While Fen is running at top speed, Merisiel is leading the zombies through tight side passages and slipping through small gaps to leave them behind.
Acrobatics to squeeze: 1d20 + 14 ⇒ (10) + 14 = 24
She dodges between them when it's time to slip out of the holding area, snatching her arms away from their biting mouths.
Acrobatics to tumble: 1d20 + 14 ⇒ (13) + 14 = 27
Finally while Fen tries to hold the gate shut, Merisiel attempts to lock it.
Thievery: 1d20 + 13 ⇒ (3) + 13 = 16