A great ending is just as important as a hook and exceptional opening chapter. The reader has been kind enough to buy your novel and read it to the final critical pages. It’s advisable to give them an ending that will kick them in their backside, and send them out to get the next novel in a series or just another stand-alone story of yours.
Excellent conclusions to the story give the reader what they want but not in the way they anticipated. It reads smoothly, but it’s not. Keep in mind of the ending of your novel’s three-act structure with twists and climaxes, reversals, impediments and new plans. When you’re novel is over, end it. That protagonist in the first act who had the excellent car and has said a few iambic pentameter memorable lines of dialogue; to the hell with them — we don’t care where he ended up.
As the ‘B’-movie master; Roger Corman once said, “When the monster is dead, the movie is over.”