As things stands, Kid and Law are lacking something to be truly capable to take down BM. They are already busting out their last ressort mode after being pushed to their limits when BM is yet to get started, and while they managed to surprise her this chapter with their awakening, and that i believe they'd continuously use even stronger and stronger moves, she should gain more knowledge on their awakening the longer they fight, and BM is also a paramecia who has an underling who possess awakening(who stated it was obvious he was awakened), so should have awakening herself.
Even assuming Kid unlocks adcoc, BM already possess her own to counter it. The only scenario where i could see them maybe prevailing is if Law uses an ultimate hax move that end up weakening BM, with Kid taking advantage of this, but the way things are going right now, it looks more like the battle will be stalled, with great feats from both side, BM ending up greatly hurt, but still looking superior unless they receive some help(Killer, Yamato, Marco are the only possibilities atm)