What is the best response to a 1NT opening bid when responder has 0 HCP and 5 clubs and you have agreed with partner to use Staymans?
Pass. 1NT undoubled when opponents likely have the values for game is unlikely to be bad. If your left hand opponent doubles and it passes around to you you can bid 2C.
Unless you have, say, five clubs and eight diamonds, you have nothing to show partner and should Pass. Given that RHO has passed, LHO will almost certainly bid and give your partner the chance to reassess the situation; if not, partner is likely to go down in 1NT, but get a better score than if the opponents made a fat contract.
There is, of course, the possibility that you are playing a system where 1NT is forcing (I can't think of any offhand, but no doubt there are some), in which case you follow the rules of the system, and discover where it gets you (and probably why such systems are rare).
You should pass.
If you feel that 1NT should be forcing, consider using the Jacoby Transfers to show 5-cards or longer in response to a 1NT opening. You could force partner to bid 3C and pass on that, though most partnerships will agree that trying to play 1NT in this case is probably better.
In this case, your partnership has at most 17 HCP, so your opponents have at least 23 points. Let them figure out if and what they want to play.