You might end it with a sense of relief, showing that the horror is finally over and the characters can return to normal. Or, you could go for a cliffhanger, setting up the potential for a sequel or leaving the audience wanting more.
You could have a final showdown between the protagonist and the monster or evil force, with the good side emerging victorious.
One way is to leave it open-ended, letting the reader's imagination fill in the blanks and create their own ending. This can add an element of mystery and keep them thinking long after they finish reading. Another option is to have a twist at the end that completely changes the perspective of the story.