I've used Casting Creme Gloss quite successfully, almost all their brown shades and none gave me a strong reddish undertone. I don't know if in your country the colours are called the same, but the Praline shade was the best on my hair and there was almost no red highlight in my hair.
I don't think a slight red when under the sun is so bad, though! It's what I love that henna does to my dark brown hair when I mix it with indigo. (:
Oh, by the way, Casting Cream Gloss is a demi-permanent dye so if she has that much white hair she might want to go for the permanent dye option of the L'Oreal brand. I really loved those dyes when I used them, lovely colours and soft hair, but remember each hair is different!
A 2C, hopefully something more as my hair gets redefined. Lots of chemical/heat damage to get rid of! Currently at shoulder length, aiming for mid-back.
(Any HtBlack you find anywhere on the internet is most likely always moi! :3)