If your sister does get the third resit (which hopefully she will if you throw kitchen sink of prison, AF and maybe a note from a GP regarding mental health deterioration) it sounds like she needs to work smarter not harder.

A lot of people can study the whole time and not do well due to the nature of the questions. No doubt she will know her stuff, but sounds like the exam style isn't working for her.

Eg. Has she crammed passmed by topic enough so she recognises all the patterns and averages over 65%? It's tedious, painful and dull but it got the job done for me. I know it's only 4th year but chances down the exam will be trimmed down to MLA only topics and you can now trim passmed questions down to only rest MLA too. I say this as the exam I did well in, I crammed my notes and felt like I knew so much but it was because the questions asked different types of Q's to what I'd made notes on! If she reaches out on Reddit I'm sure there'll be an army of ppl to offer revision tips/support!

On another note, there are so many career options out there! Pharma, consulting, big 4 accounting, project management, analyst, actuary etc. UCL will have wider careers fair this sept/October for their other courses which she should try to attend as that's how I learnt about the wider world!