Help on designing data science curriculum from "traditional" offerings
Of the traditional majors, I think computer science + statistics is the most obvious. You can substitute applied mathematics or even physics for the statistics major, if you want. Always keep the computer science courses.

If the choice is between information management and business analytics, given that you're already studying maths, it's hard to say. They're both pretty light-weight, and will add little to your math major. I would not consider them a plus per se as a prospective employer reading your resume. Unless they're cheap, I'd take online classes and get some practice instead.