I did my GSCEs seven (yeah I’m 23) years ago now, I ended up with nine of them in various subjects which nobody ever cared about. In hindsight I would have concentrated on getting the highest grades possible in my ‘core’ subjects – English, Maths and Science, since high grades in these subjects make all the difference for future career prospects… nobody cares about your A in french and foodtech if you failed your maths. Just take a look at the requirements of any college (for A levels) or apprenticeship.
I’d recommend doing the triple science, if she really doesn’t get on with physics and worst case fails it she still has two other science GCSEs at a higher level than they would be if she had done double science.
As for any other GCSEs the french is a no brainer as it is easy for her, knowing a language shows intelligence which is always good, any thing else just pick what is easy and fun for her, just to make up the numbers, last thing she needs is to be bogged down in a history GCSE when she should be putting all her effort behind those all important ‘core’ subjects.
Since this is what happened to me, I got Bs in graphic design, geography, religious education, I remember putting real effort into these subjects partly because I liked them and in a way I neglected my core subjects and came out with a C in Maths and English literature, in hindsight I would have rather failed geography for example and had an A in Maths.
Some of my friends did history at GCSE and found it rather difficult, it was a lot of effort for very little gain, PE at GSCE again a lot of my friends did that too and said it was also difficult due to it being very biology theory based.