At Home Meaning

(dated) Available to receive visitors.

Example: In one's place of residence
  Sorry Sir, I left my homework at home.
  Where's David? – He stayed at home to fix the washing machine.
  The team has won three-quarters of its games at home, but less than half of away games.
  I feel at home when I'm round my girlfriend's house.
  I'm right at home in my new university.
  He's quite at home discussing French literature.
In the home of one's parents.
  I can't believe it, she's 28 and still lives at home.
  Even though I still live at home, I'm quite successful.
1922 Emily Post, Etiquette, Chapter 10: Cards and Visits
  When a servant at a door says “Not at home,” this phrase means that the lady of the house is “Not at home to visitors.” This answer neither signifies nor implies—nor is it intended to—that Mrs. Jones is out of the house.