A specific problem that may affect some potential math majors is that students who enter very advanced in math may run out of math courses. “Very advanced in math” means completion of college course work beyond the calculus 2 / AP calculus BC level while still in high school. Such students are likely to want to take graduate level math courses and do graduate level research as undergraduates; such opportunities may be limited at many LACs.
For economics, different schools do vary on the amount of math emphasis in their economics courses. It is common for intermediate microeconomics to list calculus 1 or 2 as a prerequisite. But some schools (e.g. Penn State) offer non-calculus-based intermediate microeconomics, while others offer (often as a more rigorous or honors option, like Amherst, Berkeley, or Harvard, but sometimes as the only option, like Chicago or MIT) versions that require calculus 3 or other sophomore-level math. An economics major looking to do a PhD in economics needs to take substantial advanced math and statistics courses anyway, but math-heavy economics courses may be preferable to such a student. Schools’ on-line catalogs can be helpful here.
Perhaps the OP can describe what possible interests or general areas of interest (e.g. arts, humanities, social studies, biological science, physical science, math/statistics/CS) that the student has. Few schools (LACs or universities) are strong in everything (some areas of study like linguistics and nuclear engineering are not very common to begin with, so even many of the biggest universities do not have them), so perhaps the OP can get more relevant help in this respect by letting others know what the student’s interests are. Ideally, a school should be strong, or at least acceptable, in any of the student’s potential majors or interests, and the school’s weaknesses should not be relevant to the student’s interests.