NoAgenda,
The best answer is B. Why? Because it a standard phrase that is used to announce the end of a meeting.
A. The meeting, ladies and gentelmen, is now at the end......This means the meeting has reached its final part.
B. The meeting, ladies and gentelmen, is now at an end.....The meeting is now finished, concluded, in a situation of not existing. You are free to leave. :)