Hull and his wife, who died in her 2nd floor bedroom, remained in the house until their deaths in the 1880's. In 1889, Jane Addams and Ellen Gates Starr obtained the property and opened their famous settlement house with the help of the Hull heirs who enjoyed the idea of helping the poor. Soon after moving in, strange noises were heard among the guests of the house which were attributed to the ghost of Mrs. Hull. Addams was actually the first occupant of Mrs. Hull's former bedroom and reported hearing footsteps each night while she tried to sleep. Gates then spent a night in the room and reported the same thing. Addams and Gates then invited author Helen Campbell to spend a night in the room after which she reported seeing a "white figure" standing next to the bed at night. Subsequent sounds and reports were given by others who later visited the house. The ghost of Mrs. Hull was described as a calm, friendly ghost though and the occupants of the building eventually grew accustomed to her presence.
That trip to Hull House is sounding like a better idea every day.
As for the rumored devil-baby ghost, I've read several sources that state the story was simply a ploy of the time to keep women from marrying men of other nationalities.