Regarding to the existence of the monsters, neither Frankenstein nor the Dracula exist, and it is Walton making up a story to cover his tracks after he murdered all the victims throughout the story
Although Dracula is a purely fictional creation, Stoker named his famous character after a real person who happened to have a taste for blood: Vlad III, Prince of Wallachia or — as he is better known — Vlad the Impaler. The nickname is due to the Wallachian prince's favorite way of dispensing with his enemies.
More than 200 films of Dracula have been made
26 films of Frankeinstein have been made
Regarding to true/false sentences,
Does Dracula mean son of the dragon?
Did Frankenstein father marry of a daughter of a very dear friend?