DWP here - just retired after 40 years... PIP is massively frustrating from an assessor's point of view because they don't know the applicant and can only go on the information given in the paper against the individual set of behaviours asked.
Just to be absolutely clear. A diagnosis of any kind is not an automatic qualification unless a DS1500 (terminal illness with less than 12 month life expectancy has been signed by a consultant).. everything else is against the descriptor's.
Autism is such a wide spectrum that can mean a person could be managing life with everything from non verbal , to savant.. with every ability in between. Including co morbidities such as no mobility and cognitive impairment.
You need to go through the steps already mentioned and ask for a reconsideration. Provide additional evidence for everyone you can.
For example. Can she prepare a meal. ? This doesn't mean can she cook from scratch , it means can she put a meal in the microwave and eat. ? Physically can she get the lid off ? Mentally can she set a timer and eat the food cooked. ?
Can she communicate with her studies ? Does she understand when assignments are due and complete them ? What additional help I'd required to do this. Provide evidence of student support .. without which she would not manage Uni ?
Can she get to lectures in specific buildings without a helper .. if she can then no points , if she has a helper then provide that info .
Does she socialise ? If she can then no points but if she uses a specialist assistant to facilitate this then provide the evidence.
And so on. For each question.
Autism is not an automatic qualification. I have ADHD and would not qualify as would only amass 6 points for managing finances.. (older kids do this for me and set me a budget and deal with post)
To be brutally honest based on the CURRENT info she would not qualify. All I know is from what you have written which is not unlike an assessors remit and I see a girl who looks after herself away from home, feeds herself, lives without immediate care (although I have no doubt you do a lot remotely so THIS needs to be added) . go to the loo alone, gets to lectures, doesn't currently miss medication (not sure about this but if she does it needs mentioning ) and basically lives her life.
Am very happy to advise via DM if that assists . I will be honest with you.