49th Street is not in, or really near (for dining purposes), Red Hook. I presume you mean the Sleep Inn on 49th Street? In which case, the neighborhood you'd be looking to dine in would be Sunset Park. So you might want to re-post with that location--there are lots of 'hounders here familiar with that neighborhood.
Doesn't the QM2 depart from the pier in Red Hook. If you're looking for some pre-boarding dining, here are a few suggestions:
• if it's a weekend, check out the red hook ballfields (do a search--tons of posts) better even than the mexican/central american food in sunset park
• in nice weather, there's the fairway cafe. great views, decent but not great food. tho i suppose you will see the same views as the QM2 sails through the harbor.
• baked--nice bakery in red hook with good selection of baked goods
• good fork--i don't like this place, but many do so i'm including it
• hope and anchor--dinerish place with decent but not great food, but if you're not a new yorker, has an interesting vibe
• kevin's--haven't been, but it gets good reviews
• ikea cafeteria--if you don't have an ikea near you, the swedish meatballs are worth a visit once in a while.
• defonte's--great old-school new york italian sandwich/hero shop. closes early.
all of these places (except perhaps the ikea cafeteria) have been discussed on chowhound. do a search for any that interest you.