I strongly feel Kaplan is a better representation of what NCLEX is really like. Problem is you have to be able to critically think through the questions. Is there some other reason this person may not be doing well? Are they getting worked up, bad test taker, have there been life events that distract them? It could be the material or many other things.
Make sure your friend reads the tips on how to break down the NCLEX questions. So helpful, these tips can be found in most NCLEX prep books. Best part is it teaches you how to weed out extra information in the question that is not pertinent to the actual question. Good luck to your friend!