RE: light weight arrows
Without knowing all the specs of her bow ,such as type of cam/cams,brace,axle to axle length,let-off,release or fingers,d-loop or shooting off the string I can only make an educated guess.
If your looking for speed look into the Easton Redlines.
I used my AA program and came up with an Easton Redline 1000.The weight is around 217gr and should get into the neighborhood of 225fps.
Like I said without knowing all the specs this is just a guess.