Muramasa
Best Girl
We can disable their powers and abilities with grief. I'm pretty sure that they need to have their soul gems on them in order to actually transform. Willingness to kill or no, Sabrina can reduce their bodies to chunks of meat and bone very quickly with her grief bending. We would be watching them like a hawk. A single thought to Homura, and they'll be stuck in timestop. Heck, we can even bring the hyper-competent Mumi to watch over them with us. We would control where exactly we would be taking them. Etc.
Meanwhile alone at home without supervision, they can easily subvert the house arrest with preparation, intelligence, and pre-cog.
Homura's fears of them pulling something with Sabrina out with them is basically irrational, imo. Which I thought was kind of the point.
I would dispute about half those counter measures. We can't really use raw grief to disable O and K's powerset. Active grief is plausible but too slow given the situation. Weather or not O and K can transform without their gems is untested. Technically they are their gems and their bodies would be in range so I don't see why they can't transform. Our own grief bending is vulnerable to Kirika's antimagic. If we have enough of it in the air, it could very well be hundreds of basketball sized grief orbs falling on everyone.
However I do agree the moment we call Homura, it's an instant win. And the end result would probably amount to a dead Oriko and Kirika. So... of course as has been mentioned the real problem is convincing Homura of this.