Assuming:
--They actually have a reason to fight
--They both have time to prepare, to even out the higher preparation time required for spellcasting for Nita, and to let Hermione use her 1337 Research Skillz
-They don't immediately forget about fighting and start comparing their respective systems of magic

Neither one is allowed to call on allies.

Who wins?

I think I already said my money's on Cluny if he goes against mortal Drip, as Drip's a serial rapist who, according to what I've seen of canon, only kills women he attacks, who are presumably helpless. Cluny has battle experience, and as was mentioned before, a frickin poison tail barb. Now Demon-Drip, on the other hand, would have a much better chance, but I'd still say Cluny, simply because he's better equipped and Drip doesn't have much in the way of power. His only advantage would therefore be size.

I propose my own, now. Joel Calley (with Miranda's help) from the webcomic Concession versus Damien from El Goonish Shive.

But as I have no real knowledge of either of your combatants, I will pose a fight of my own.

100 Red Shirts (Star Trek) vs. 100 Stormtroopers (Star Wars)

I've never read the Redwall series, but I'm pretty sure Cluny the Scourge is some kind of warrior. Drip was just a crazy murderer in life, who controlled his victims with threats. That wouldn't work on Cluny, and Cluny has the advantage of combat training that mortal!Drip couldn't match.

I don't know anything about Drip, so I'd have to say Cluny by default.

I will bring up that his habit of wearing a poisonous spike on his tail would probably end up being a lethal surprise to his opponents. Is there a restriction on weapons or armor?