Aunt Adah is the kindly old farm woman who greets Voyager's abducted crew aboard the Caretaker's array, part of an illusion meant to keep them calm while they await examination.
Aunt Adah appears in Caretaker, the feature-length opening of Voyager. When the crew are swept from the bridge to the Caretaker's array in 2371, they find themselves not in an alien facility but in a sunny farmyard, where a cheerful elderly woman welcomes them with lemonade, corn on the cob and an invitation to sit down and rest.
She is not a person at all but part of a holographic setting the dying Caretaker uses as a waiting room. Her task is to keep the visitors content and away from the barn, where the real machinery is hidden.
Once Paris and Kim find their way inside, the pretence is dropped: Adah's manner turns cold, she tells them they are not yet ready, and the farm folk close in before the crew are taken for the painful medical tests.