Legal Question in Employment Law in California

It doesn't sound like they did everything right, but based only on the facts you have provided, a lawsuit against the Company would probably not be worth it. What do you mean by hostility? Was the individual accused of being hostile toward other coworkers due to their membership in a protected class or was it a supervisor. I can't really help you unless you are a little less vague on the facts.

What if?

In CA, you are an 'at will' employee that can be disciplined or terminated at any time for any reason. A misconduct complaint against you, unless proven to be entirely false and known by the company to be false [not just denied by you], is "grounds" for discipline or termination above and beyond 'at will'.