One of the Ally missions for Sofia Daguerre will require that you retrieve the Serum Z from the West Tex Research Center and bring it to her. Here we have the complete walkthrough Fallout 76 Wastelanders Ally: Past Expiration to help you out.
Fallout 76 Wastelanders Ally: Past Expiration
Once the Past Expiration mission starts, you will have to speak to Commander Daguerre. She’ll ask you if you’re with her on this.
You will have to select the first option where you promise her that you’re with her on this, and she will ask you to call her Sofia.
The next options you’ll be needed to select are: “I’ll find this serum, Won’t take long” And “I’ll be back later, Sofia”.
You can select other options as well to try and see how she reacts to everything you say, but neither of the other options that you have will allow the conversation to proceed.
West Tex Research Center
Once you’re done, you will be rewarded a couple of items, after which you will have to select Ally: The Woman Who Fell To Earth from data. Open up your map and fast travel to the National Radio Astronomy Research Center.
Once you’re here, head towards the facility on the map which has the Retrieve Serum Z highlighted over it.
Once you’re here, you will run into a number of hostile units, who’ll begin to shoot at you. Try and kite them out of the facility and put them down one by one.
Try taking down the ranged enemies first since they’ll be very annoying. After you’ve cleared the enemies, head to the door of the West Tex Research Center and enter the facility.
Go straight and proceed to the terminal here. Open the door on its right using the terminal and head inside. You will run into a number of Super Mutant Masters here.
Proceed further while fighting off the enemies that you encounter. You will enter a kitchen-like area with a number of cabinets and counters.
The cabinet will have the Serum Z in it, take it and leave. Once you go back to Sofia to bring the Serum Z to her, complete the conversation with her after you interact with her and you will have completed the mission.