When Eddie tells Mrs. Livingston that she is just like a mother to him, Mrs. Livingston knows that it is time for her to leave the Corbett household for good. She doesn't want to be an obstacle for whoever the eventual Mrs. Corbett will be in the lives of either Tom or especially Eddie. So Mrs. Livingston quits immediately and tells Tom the reason. However, Tom still needs a housekeeper and Eddie still needs a caretaker. This is evident the day after, when the first disaster happens when Eddie needs to get dressed (Mrs. Livingston used to pick out his clothes), and the second when Tom tries to make breakfast. Norman comes to the rescue, first in helping Tom write a help wanted ad despite the fact that Tom has already written and submitted one to the newspaper, and second in providing advice on appropriate living and housekeeping for the modern bachelor household. Luckily for Tom and Eddie, they don't have to heed Norman's advice as the perfect housekeeper answers their ad: Mrs. Livingston. In reality, she answered Norman's penned ad.
—Huggo