Sentence B is the correct option. When using "however" to write a compound sentence, we should write a semi-colon before and a comma after it. When "however" is used at the beginning of a sentence, we should write a comma following it.
Answer:
There are many types of monsters in this world, monsters who will not show themselves and who cause trouble. Monsters who abduct children, monsters who devour dreams, monsters who suck blood, and, monsters who always tell lies.
Explanation: