Mu has alot of capacity to setup frame traps with her lasers, but the only one you can really abuse with her normals is off her 2B. 2B has great range and recovery so properly spaced 2B>2B can be really good. Up close 2B>2A creates a 6 frame gap which will beat most low pokes, however this is not enough to stop bang 5f 5A. Typically against any character with a really skewed damage output (like bang), I would just do a block string and get the heck out of there.
Check the combo thread for combos, if memor servers the GB combo is (from zeromus):
Males:
63214C (fully charged), dash 6B, 6A, 2C, jC, j2C, [2B, 6A, jC, j2C] x2, 2B, 5B, 632146C (~5.5k, builds 45 heat)
Females/Bang/Hazama:
63214C (fully charged), dash 6B, 6A, jC, j2C, [2B, 6A, jC, j2C] x2, 2B, 632146C (~5.3k, builds 42 heat)