Hi, I did a degree in Archaeology and graduated in 1002. In my A levels I did Chemistry, Geology and History, but dropped History as I had a huge clash with one of my teachers. Before I dropped history I spoke to many advisors who told me that a History A level wasn't necessary to get onto the Archaeology course I wanted, but I would check with the university requirements depending on where she wants to go. Also be wary of the course content as I liked the practical side, yet my course turned out to be almost all theory.
Quite a hard profession to get into at a top level moneywise. I was told that to get an ok job in a museum I needed at least three years practical experience, which would probably come from working abroad excavating in which you get paid a pittance, although they will probably pay for your board.
After my degree I then decided it wasn't worth it and am now a primary teacher. I suppose it depends on how passionate she is about archaeology and how far she is willing to pursue it.
Hope this helps.