Advanced mathematics (calculus), linear algebra, probability theory and mathematical statistics are compulsory courses for all science and engineering majors.
Mathematical methods are more difficult.
Generally speaking, group theory and topology are not very demanding for undergraduates. Graduate students want to learn modern physics and need to master it.
According to the degree of difficulty, the order is:
Fundamentals: linear algebra, probability theory, mathematical statistics.
More difficult: mathematical methods
Extensibility: group theory, topology
If you are studying difficult math classes such as group theory for the sake of learning physics, you'd better not read math textbooks. You'd better find math books written by physicists in this field, otherwise you may still not understand them. )