I'm sure Atticus had no desire to spend much time with the ladies of the missionary circle, and he had not planned on being home until they were all gone. He greeted the women but then excused himself to the kitchen, asking Alexandra and Miss Maudie to join him. His "face was white." Atticus had received some bad news: Tom Robinson was dead, shot by prison guards as he was trying to escape over the fence.
"They said he just broke into a blind raving charge at the fence and started climbing over. Right in front of them--
"... Seventeen bullet holes in him. They didn't have to shoot him that much..."
Atticus had come home early in order to get Calpurnia, who he wanted with him when he went to break the news to Tom's widow, Helen. Calpurnia left with Atticus, leaving Maudie, Alexandra and Scout to serve the remainder of the refreshments.