The commodity sector is in meltdown:
Cash is king. There's no such thing as cash in a brokerage account so near-cash: T-bills, short-term Treasuries, German/Swiss bunds, Money markets, are safest, although nothing is 100% safe. Liquidity is key.
Those in put options/volatility calls, need to be mindful of counter-party risk and broker risk as experienced back in August when many brokers broke literally. By the end of this, every broker will be offline. And whatever positions exist at that time will be frozen. Doesn't mean the money is gone, but moving it around may be difficult for days or weeks.
Counter-party risk will be extreme. Many/most banks will fail. Most people will eventually get their money back but we already know there will be "bail-ins" aka. haircuts for depositors.
Invest at your own risk.
http://ponziworld.blogspot.com/2013/07/surviving-deflationary-crash.html