Rihaku
The Internet
I'm against assassinating the Infernals; whatever the risks of their continued existence, Ayala is a member of House Mnemon, so if we kill them... well. An investigation would be launched, and Syn would probably use that to discredit us or get us killed, as Mnemon has close ties to the Order. It's not a good situation, really. Pitting Polemgaus against Ayala is probably the best idea, hit two birds with one stone, but it's difficult.
The problem is that all that effort is wasted if Ayala simply decides to stay after losing / wins. Nilul will still be panicking and the Infernals will still be here.
As we're asking questions for Nilul: Given her knowledge of Ulyssian's general capacities as well as the theoretical ones of the Infernals better than Ulyssian: is assassinating them both relatively possible/easy?
That completely depends, she doesn't know their Essence level or anything. They're here, though, which doesn't imply that they're weak.
Also is it within her capacity to handle the social and temporal repercussions of such an act? Given they may already know things she wouldn't want them to and may thus need killing in the immediate future.
She can probably brainstorm a few ideas when she isn't panicking, but likely you'll need to contribute some ideas well.
Does Nilul need to be present as our second, or can she be elsewhere. If she does not need to be present, she can disguise as someone else, so even if the infernals spot here, they won't connect her to Nilul.
Also, do we have any method of swiftly contacting Zao. He could arrange for an emergency that requires us to go back.
It would be strange if she weren't present, but strange may be better than showing her face.