I think you have been given some good advice. I like the 3 rules of conversation -- (1) Is it true? (2) Is it kind? (3) Is it necessary??
Be strong for yourself and take care of you by setting some boundaries or rules which are yours to maintain. That you have a business "No quilting for free" is an easy rule, If she would like to pay, first let her know that you would not be offended if she wished to use another quilter, but that there are expectations that you and the other quilter(s) would expect in a top ready for quilting. You don't need to go into issues unless "A" wants.
Understand that your time is your time to spend as you wish. It is ok to enjoy her company without doing her quilting. If she persists you may have to make the decision (or give her the choice) to not discuss it further, even if that means no longer visiting.
Good luck!