What I do when I miss some meetings or when I'm asked to do something like the carts or help in the maintenance work of the Hall is simply to say that I'm busy at the moment and not available because of a personal situation/my job/a course required to attend by my employer or something similar. Don't give more details.
If they ask how are you doing or if you have some problem, let them know you're fine but busy.
I prefer text messaging than phone calls as they (especially elders) always want to get some information about you. Giving out details is quite dangerous especially with friends or people you may feel comfortable with.