We have this ol' WoJ gem which I believe can be applied:
Hmmm. In terms of pure, raw power, several who have appeared or been mentioned in the books could pull it off, though neither side would really “win” as much as “continue to exist.” Plus, the sudden absence of Mab would do freaking HIDEOUS things to the earth. But here’s who has the necessary horsepower do it:
o Titania–though it would be a coin toss. Almost literally.
o The Mothers (who wouldn’t)
o The White Council. As in, ALL the White Council. Every wizard on the planet. And they’d need her Name.
o Drakul.
o Ferrovax.
o The Red Court–again, ALL the Red Court, though their odds wouldn’t be good.
o The entire White Court–very, very long odds on that, but if they actually pulled it off, whoever took Mab would effectively control her power.
o Cowl (if the Darkhallow had succeeded).
o A union of the old Elders of the Black Court. They were freaking scary until the Whites arranged to have them hounded down by mortals.
All of that, of course, assumes that Mab is standing there alone, outside of Faerie, and not commanding an entire nation, literally millions and millions and millions of nightmarish creatures of every description. Which she does.
There’s a REASON that when Mab said, “Sign these Accords and abide by them,” people listened.
*****
Shift back... if it would take the entire White Court to overcome Mab, I can't see enraged Thomas taking on a Titan without significant assistance. Now, you wouldn't need Thomas if you already had Alfred. Unless somehow the Titan is weak to White Court power. So can't see Thomas really helping there.