OMG, that's libel. Calling Mrs. Smith a liar on National Television. I'm hoping Mrs. Smith sues the pants off Matthews. Not that he even wears pants under that table.
And how many times did the Ambassador ask for more security? Fell on Mrs, Bill Clinton’s deaf ears!
You may have a point about libel. Mrs. Smith is a private person, not a public figure. Mrs. Clinton is a public figure. It is protected speech to say just about anything about a public figure, but it is not protected speech to do so about a private figure.
So there might be a valid libel claim against Chris Mathews. There might even be discovery to see if there was collusion with the Clinton campaign. Did Chris give money to the Clintons?