Thanks for posting your question in the Microsoft Q&A forum.
Adding C: Typically, new members added to a DL after the invite was sent will not automatically receive the meeting invite. You would need to resend the invite to the updated DL or specifically send the invite to C.
Removing A: If A is removed from the DL, they will not automatically have the meeting removed from their calendar. The invite exists independently on A's calendar. You would need to manually remove A from the meeting invite or ask A to delete it themselves.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.