Straight out of the manpage for mke2fs:
-c Check the device for bad blocks before creating the file system.
If this option is specified twice, then a slower, destructive,
read-write test is used instead of a fast read-only test.
As I interpret it, mke2fs will try to force writing to the bad block. What happens if it doesn't work I don't know - most likely the whole formatting process will fail. But shouldn't you be considering getting a new disk if it is starting to fail?