I got asked about doing a weeding cake for 200 people and she want to know if she could use her quest card (which is food stamps) to pay for it.

Um, this has already been covered in the 1000-post long thread. Enjoy:

http://cakecentral.com/t/751860/things-not-to-ask-say-to-a-baker

AI can only assume that you do not take government assistance for making your baked goods so I would just tell her you don't do so. It is also illegal for you to do so , so simply inform the person who's asking you to do this that you don't feel comfortable breaking such a law.