Trying to arrange events when only one member of friendship circle still works

A tricky one. Your friend is obviously struggling financially and having to work 2 jobs in later life. As eazybee has said it must hurt and could affect her continuing as a member of the group.
But that isn’t the fault of the group and so would advise carrying on as before but try to arrange outings for weekends or when your friend is available that don’t cost much or are free.
There really isn’t a good way to square this circle.

Try to incorporate activities she can afford in her free time, activities when she is working to suit the rest of the group.
It depends how much you value her friendship; have to say this will probably destroy her membership of the 'friendship' group.

I can tell you, it hurts.

I imagine your friend is a bit resentful knowing she can’t join in. Woking when ‘you have to’ rather than choice must be a hard stone to swallow.

I think communication is key. You’ll need to lay your cards on the table. It’s not your faults that as a group you are all able to do things together. I think with tact and empathy you could navigate this by asking your working friend how she would be most comfortable. Would she like to be continually asked or rather not know? Would she prefer to set out her non working timetable so you all know where you’d be up to? Could she tell you what activities are her favourites then you could all try to incorporate them into your plans.

A difficult conversation admittedly but better to grasp the nettle I think and deal with it rather than upsets all round more often than needed.

Basically, you just carry on with your plans. Why would you all put your lives on hold to facilitate one person? OK, so they’re still having to work due to financial issues but it is small minded and unreasonable of them to expect the rest of you to sit home twiddling your thumbs until they have a day off!

Just make sure you arrange some things for her days off that are also free. An evening walk maybe? Or a Sunday picnic.

And don’t spend those occasions talking about the other things you have all done! Maybe that’s what’s making her feel left out?

Do some things with her and some without her. Perhaps the occasional Saturday outing if she does not work on a Saturday. The woman who runs our WI refuses to arrange and afternoon meeting and insists we have it in the evening as they have had for 60 years. There are now only two ladies who work. If she had afternoon meetings the elderly members would not be falling away.