Questions often come up about closing prayers at the end of group meetings. The question has been raised at the national level several times over the years. In 2009 it came up again and was discussed at length. The bottom line is that this is up to each individual group to choose what to do at the end of the meeting, and the "group conscience" must be the guide.
The most common choices are the "Serenity Prayer", the "Lord's Prayer", the "Al-Anon Declaration", and simply a period of silence. All groups are encouraged to take a "group conscience" periodically and this is one question that can be brought up at that time. Documentation of the World Service Organization 2009 discussion on this can be found on the Northern California Al-Anon website at this link ---> ClosingPrayer.