She hasn't done an A level early, with Maths, you just have to seat 6 papers. Commonly, pupils do C1 and C2 first year, with C3 and C4 the following and then either Statistics in year 1 and Mechanics in Year 2 or vice versa. However, some will also do C3 and/or C4 in year 1 just because it is possible to resit them the next year without it being counted as a resit and only the best mark will be counted, hence nothing to lose approach.
Some modules are also the same in Maths and FM and it's possible to count a FM course grades towards Maths. This is what DD did as she dropped FM in Year 13.
The way it works is that you have to get the same total score to get an A or A, but to get the A, you need to get at least 90 in C1/C2/C3/C4 (hence swapping between Maths and FM).
DD just managed to get 90 in C4, so just scrapped the A*.
You need to find out what grade she got for each module. the 'C's are what matter most. Mechanics/Statistics not as much if she can get over 90 in all Cs.
If she got say 90/90 in C1 and C2, but 50 in Mechanics, she is still just about ok, but considering she can't go lower, she might still want to redo C1 and or C2 to push these up, that is if her teacher thinks she can do it, otherwise better to focus on C3 and C4 next year.
Hope it makes sense, my brain is fried this morning!