FYI: the relay in a 1996 C class is mounted in the trunk behind the battery.
The door panel has a Phillips screw under the armrest, one under the optional SRS badge, one in the door lock trim and one near the doorhandle.
The speaker grating has a screw in the bottom after which it can be pried out (starting in the lower, outer corner)
The bottom and side need to be pulled away from the door (fastened with plastic clamps) and the top needs to be pulled upwards to get it released.
with a minor 600+k