The main difficulty, as I see it, is your friendship in this arrangement. If it was a situation concerning strangers you would treat this as a job, do your best, accept a fair amount of pay for your efforts and not be too concerned about the end result. I guess I am saying that whether Holly should, or should not proceed with the course is not really a decision for you to make. I don't think you should personally agonise about whether she is wasting her time (and yours). Although it may be difficult for you to avoid, giving her so much help that what she achieves is as much about your input than hers is (IMO) wrong. My advice would be to treat her as you would anyone else. If she can't make the grade she will soon come to realise this for herself. Alternatively the course assessment procedures will solve the problem for you. When this happens be a good friend and offer "a shoulder to cry on".