Since you've already chosen Indo-Pak History, history of USA is not an option as you can only pick one subject from that group. Out of the subjects you have mentioned, I would suggest Gender studies purely because I recently prepared for it for the upcoming exams and it was an interesting subject to cover. At the end of the day, it depends entirely on your inclination and interest. I personally don't believe much in scoring trends. A subject is scoring only if YOU make it scoring. You should look through the courses of the mentioned subjects and chose the one that interests you the most and appeals to your academic background. You'll have to put hours into the preparation anyway, why not enjoy it and use this as an opportunity to learn something new and worthwhile?

Anyway I wish you the very best of luck!