The Huxtables are coming back, for sure. NBC has confirmed that the two-hour reunion special, “The Cosby Show: A Look Back,” will air on May 19, the final Sunday of the May ratings “sweeps” and of the 2001-02 season, reports Variety. And that particular night, the trade paper reports, is shaping up to be a veritable battlefield for viewer attention. Besides “Cosby,” the Sunday showdown features the two-hour series finale of Fox’s “The X-Files,” the two-hour season wrap-up of ABC’s “The Practice” and the three-hour conclusion to the CBS reality hit “Survivor: Marquesas.” That one week’s ratings help determine future advertising rates, so stakes are very high. Though NBC is already well established as No. 1 this season, the bigger its overall ratings, the more money it stands to generate. Sunday, however, has traditionally been a weak night for that network, so, Variety notes, a return of “Cosby” is almost guaranteed to fare better than regular NBC programming. NBC researchers believe public interest in a reunion of “The Cosby Show,” the smash ’80s family sitcom starring Bill Cosby, now 64, is stronger than that for the other programs on the night and could translate into a ratings win among total viewers (though not the young adult demographic NBC, and all networks, covet). Most industry analysts believe “Survivor” and “The X-Files” will slug it out for the ratings crown among viewers aged 18 to 49. To improve the chances for “X-Files,” Fox will run the season finales of “The Simpsons” and “Malcolm in the Middle” as lead-ins that night.