Match the book to whatever deck she’s using. If it’s Thoth, Lon Milo DuQuette’s Understanding Aleister Crowley’s Thoth Tarot is good, or Gerd Ziegler’s Tarot: Mirror of the Soul. For Marseille, Yoav Ben-Dov’s Reading the Marseille Tarot.
I’d suggest sticking with one deck and one book for like a month, so the meanings don’t get confusing.