In fact, Batha, along with other scientists including Doctor Hendricks, had been kidnapped by batarians and brought to a research facility on the Ahn'Kedar Orbital Platform. She was told the batarians were suffering from a terrible blood plague that had devastated entire batarian populations, and, moved by their plight, agreed to help create a vaccine against it. She didn't realise the "blood plague" was actually a bioweapon the batarians intended to unleash on the Citadel.
While Batha worked in a separate facility to develop a prototype formula of the vaccine, her colleagues found their labs under assault by Jacob Taylor, who fought through their batarian captors to reach them. However, Jacob provided a distraction for Nax — with whom he'd joined forces — to blast his way through to Batha and carry her out on his shoulders.
After Jacob took out the pursuing batarians, Batha expressed gratitude to Jacob, much to Nax's dismay. Batha claimed she was close to completing the vaccine, but that it was still not ready for use. She could come close with some items from the sick bay of Jacob's ship, but the final vaccine would also require a large amount of unrefined element zero, which is rather difficult to come by. Fortunately Miranda had a lead to such a stockpile on Bekke.
Batha eventually completes the formula, just in time to cure Illo Nazario and administer a vaccine against the batarian bioweapon to the rest of the crew. She later used it to inoculate exposed victims on the Citadel.