The last thing the house says in Ray Bradbury's short story is the following line:
Today is August 5, 2026, today is August 5, 2026, today is. . .
The line wraps up the entire story in a nice way because it reminds readers of how the story began. By the third paragraph of the story, the house is already talking. It is announcing to the inhabitants of the house what day it is.
"Today is August 4, 2026," said a second voice from the kitchen ceiling, "in the city of Allendale, California."
The house must start every day like this. My guess is that announcement functions like the alarm clock for the family who lives there. From the date announcement, the house continues to update inhabitants about important things that need to happen that day. It's basically a step up from somebody's Google calendar sending reminders via email.
The story ends with the house making the same announcement with which it started. It's just the next day. While the house seems intelligent and emotional at times, the final lines of the story strongly remind readers that the house is still a machine. Despite the horrific deaths of the family and the consuming fire, the house is still trying to act like everything is normal. It's a sad and lonely way to end this story.