A witness can only take the Fifth as to specific questions if the answer to that question would be incriminating.
Stonewalling the House Intel committee entirely is actually a high risk strategy for Flynn.
Flynn's most serious downside comes from the criminal sentencing he has coming up.
Flynn also seemed less than fully cooperative with DOJ during a recent trial.
You can read it yourself: politico.com/f/?id=0000016c…
I don't expect the Judge to look favorably upon this motion.
House Intel should aggressively push to enforce its subpoena before Flynn is sentenced, so the judge can consider Flynn's words and actions in response when he sentences Flynn.