If I write about a “mainstream” woman in history like Susan B. Anthony or Alice Paul, will that be seen as too repetitive in admission officers’ minds no matter how good the essay?
Likewise, if I were to write about a conservative woman like Anita Bryant or Phyllis Schlafly…are Barnard admissions officers looking for someone liberal?
It’s hard to say what someone will think if we can’t see the quality of the writing or the POV. I don’t really think that the topic is as important as what you do with it. Colleges want to round out their classes. If you are conservative and you write passionately about a conservative hero of yours and convincingly write about how much you want to attend Barnard, then that could be interesting. They’d have to feel your passion for both, however, and that your thoughts were well reasoned. best of luck.
I agree with Dustyfeathers - it’s not so much about who you write about, but how you do it. With the exception of maybe Hermione Granger, who they’ve likely gotten hundreds of times, they’re not likely to admit or reject you based on what woman in history or fiction you choose, even if their politics seem to disagree with Barnard’s own mission. I’d also like to add that you don’t have to choose a woman that you agree with or even admire - I remember reading about a girl who’d chosen Phyllis Schlafly precisely because she disliked her, and wanted the opportunity for a discourse and debate. In the end, it’s most important to pick somebody that has something to do with you. Ada Lovelace was a remarkable woman by all accounts, but I personally have no interest in STEM, and therefore it wouldn’t make much sense for me to rave about how much I wanted a conversation with her. As long as you write convincingly and with passion, Barnard will consider you on the same level as everyone else. Good luck!
@sarahharty @Dustyfeathers okay. Thank you so very much!!
My D wrote about Alice Paul and was accepted!
I was accepted RD writing about Hermione Granger 
My D wrote about Leslie Knope from Parks and Rec and she was accepted!