It did not really compete that much. The target audiences and target domains are really different.
C was invented as a replacement for assembler to portably write operating systems and applications in a slightly higher-level notation.
Lisp was invented as a tool for computing with symbols (computer algebra, theorem prover, game playing, natural language processing, expert systems, knowledge representation, ...).
when the Lisp Machines were invented in the mid 70s (as personal workstations for research programmers mainly in AI) and commercialized in the early 80s there was nothing to compete with. When alternatives were available, there was no longer the need to have those (and they were not competitive), so they died away.
C was invented as a replacement for assembler to portably write operating systems and applications in a slightly higher-level notation.
Lisp was invented as a tool for computing with symbols (computer algebra, theorem prover, game playing, natural language processing, expert systems, knowledge representation, ...).