You've already received some great responses. For what it's worth I'd like to add;
There isn't much a nation could do to protect from volatility since any national controls don't protect it from all the trading done globally. Also, any controls put in place by a nation might only serve to add more volatility to the market. To some extent, the volatility is due to immaturity in the market. I've read that an introduction of more short pressure would decrease volatility through puts, more short selling. This naturally creates increased resistance so prices don't become hyper-extended.
As above, hedging could be done with options once the market matures. This would protect a company investing in bitcoins. There isn't a natural counter-play so when Bitcoin drops it isn't automatic that something else would increase. Perhaps a basket of 'blue chip' coins like ZCash, Dash, Monero that trade vs. BTC might work. At the moment the best approach is to use the volatility in your favor by buying heavily in deep dips so you end up being less sensitive to the daily price action volatility.