When did you get told she hasn't got it? Are you still in time to do a mandatory reconsideration notice? You can ask for an extension too - if you phone them.
If you've got time to do a mandatory reconsideration notice then go through each point and tell them why you think they are wrong...
For instance one of the questions is about taking mediaction isn't it?
You need to say "x cannot take her own mediction - she needs prompting to take this at the right time of day and in the right quantities. If she is not prompted she does not take the mediction and this results in an instability of her mental health which leads in turn to suicidal thoughts etc etc" - even better if you can say "this is outlined in medical report ...."
Same with eating - "x needs prompting to eat and to prepare food for herself - if she is not prompted or helped to make food then she will often skip meals - this leads to .... etc etc..
Same with the finances. "X cannot budget accordingly and spread her funds out to meet her needs. She is likely to spend a months' money in one go not realising that this means she won't be able to buy food pay bills, rent etc - this in turns leads to high anxiety caused by demand letters and a failure to look after herself - no funds to buy food can lead to ....
Do you see where I am going here?
There's a guide here...
focusondisability.co.uk/benefits-and-allowances/pip-assessment-points-a-guide/
Work out your answers (without lying) to fit the points you need in each section...
...ALWAYS talk about the worst day - such as going food shopping if she has taken all her drugs and had breakfast and is feeling great - no problem - what if she is anxious and depressed and feeling suicidal - she'll need help won't she?
Not sure if this helps you - I do a lot of PIP claims in my job - 100% award success rate at the moment!