Reseting the light isn't a matter of replacing any particular thing.
It depends on your car/SRS version as to how the problem (the purpose of the light is to indicate the system is shut-down due to a problem) is diagnosed. Early versions up through 1987 have no accessable self-diagnostics and must be circuit tested (preferably with the MB tool). From 88 through 93 self-diagnostics was through impulse codes readable with simple tools. From 94 on the systems are digital and can only be addressed with a scanner.
Fault codes suggest diagnostic strategy and the components are tested and when the problem is fixed the codes are reset and the light should go off after each self test (key cycle).
Bosch Master, ASE Master, L1
33 years MB technician