Maybe first clarify with her whether her offer of $12 was for the labor only, and was she intending to pay for the supplies. If not, let her know that you can give her the supply and fabric requirements and she can pay for all the supplies, and agree to do it for $12 for the labor(or free if you want to donate time). Also you could offer to accompany her to help select the fabric and supplies if she would like help with that. And you could also give her a list of some places she can take some quilting classes so that she can learn to do it herself.