The Big 3 in sociology are Marx, Weber, and Durkheim. If she’s got a handle on Marx, especially texts like the mss. of 1844, she’s got a better start than most. For Weber, The Protestant Ethic is a good starter. For Durkheim, either Division of Labor or Elementary Forms of Religious Life. Of course there’s lots more recent stuff, but everyone still references those.
Did you ever drink Baileys from a shoe?