I am wondering if it is time to suggest

a group should be closed.
I would regret doing it but it has become smaller and, much as it has been enjoyable, I think it may be coming to its useful end.
We have been meeting once a month in the local bookshop for a very long time now. I was first asked to get the group going by the previous owner. She set up other groups as well, reading groups, writing groups, discussion groups, an embroidery group and the knitting group.
People have come and gone. That is the nature of such groups. One friend came on a regular basis until she moved back to the US. Another has moved interstate. Two more have moved to other locations in the city. 
We have not seen one member for some months. I know she has not been well but there was no response to an earlier message inquiring how she was faring.
People have come once and decided it was not what they wanted or they simply got the help they needed and didn't feel the need to return. That's okay. It is part of what the group is about.
Yesterday another member of the group phoned me and said she won't be back for the moment. She is elderly and has medical issues which now prevent her from getting there. Another only comes if someone picks her up. 
Someone else, who does an amazing job of getting there at all, has meetings today. 
People who tell me they want to be there forget that it is the last Tuesday - not the fourth but the last. 
I'll see how many people are there today and next time - which will be the last time we meet in the year anyway  - and then discuss it with them if the numbers are still right down. It's not fair on the bookshop to have so few.
I'd be sorry to see it go because I know the few who come on a regular basis do enjoy it. It has been a group almost completely without friction. The only potential source of friction removed herself from the group some years ago and won't be back. 
It has served a purpose, just as the group at the library serves a purpose.  
You can carry things on for too long.