Depends on what they are looking for within Excel Mike. Anything by John Walkenbach on formulas, charts or VBA should suffice, Debra Dalgleish for pivot tables/charts. If they want Power BI/Query/Pivot, that is a bit harder to recommend a book.
I didn't register at SAM, I have more than enough registrations spread over the net, but I did look at the other site.
Obviously I have gone too deeply into the classes/exams, but I am thinking that no one book will get you to a level that you need to pass the exams. The accountancy modules will probably need formulas, especially financial function formulas, some sort of data gathering (connecting to an external source, import from files, or input within Excel), and some sort of analysis. The Business Information Systems would require that and charting, pivot tables, and maybe the power tools.
Books can give you methods, but unless you have projects to practice them on, either work projects or your own interests, then those techniques will not be mastered.
Would the BINS 1310 class not offer a better starting point?