Handing around mind blanks will stop the confusion and evil gaze effects. Freedom of movement will also help with the gaze, its hold monster ability, and make that +34 grapple modifier look a lot less threatening. Greater dispel magic may help to bring down some of its ongoing effects, but with that caster level, don't count on it. Everyone enjoys haste. Everyone fighting a sighted opponent enjoys displacement. The nightwalker's see invisibility at will is nice, but it can't see through obscuring mist or a fog cloud, and if it doesn't already have that buff up (or if that buff has been dispelled), invisibility and its derivatives will cost it an action if it wants to see the beneficiaries. As high as the nightwalker's Spellcraft modifier is, don't expect to fool it with illusions of conjurations, but absolutely use them to distract summoned (and stupid) shadows or greater shadows... even dread wraiths, while not idiots, can't identify a spell being cast.
There may be other options, depending on what advanced learning was picked, equipment owned, and how the fight goes. Basically play buffer for the party and try to waste or undo the nightwalker's actions as much as possible. If the beguiler is redundant with another party member for this, that's fine. Either B takes some pressure off the ally so they can do other things, or they get their party boosted in half the time.