perhaps, but match 11, being able to cross a city before a bullet reaches it target shot from only a few feat away, blizting around the world ect. suggest speed well beyond what the hellfire can deal with.
According to Chris Claremont, the speed of thought is faster than light, IIRC. early 2000's X-Men run. Xavier has detected super speedsters in the past and from what I gather, Cassandra is more powerful than him.
I think Emma and Cassandra have what it takes to take him down in a psychic battle. It will be one hell of a fight, though.
Fernus fought an army of telepathic, invisible, shapeshifting supermen for the heck of it... and killed all of them. Then got bored and stomped the JLA.
According to Claremont, physics (and common sense) are for chumps.
Regardless of how long it would take "thought" (in this instance, referring to thoughts traveling from one brain to another) to work, "thought" (in this case, the activity of neurons activating in a brain to actually compute what actions to perform and allow the body to carry out) would still work vastly slower than light.
In other words, while Cassandra Nova's super powers may activate and register brain activity before Fernus wrecks her, her own brain wouldn't be able to compute the information to actually perform any actions (telepathically attacking him, warning her teammates, etc) in time.
Also, given Fernus' own formidable telepathy, Cassandra Nova would have a hard time dealing with him even if he stood still. Obviously that won't happen, so the point is moot regardless.
Those people were never in the hellfire club's inner circle, Emma hallucinated them.
Cassandra Nova wasnt just a telepath, she also had intangibiltiy, regeneration, psionic energy armor, telekinesis and a matter desintegration power. She walked through the Shiar Imperial Guard with Gladiator in it and had the mummudrai powers of body shift and possession on top of TP on par with chuck's. She can hold him at bay, and with Emma on her side, they can likely mindrape him too. I actually believe she can win this on her own. Dont recall Fernus himself blitzing anyone either, but it could just be my memory.