More generally, in times where people would rather have useful things like food, tools, and gas than pieces of paper you'll be screwed if cash is all you have - because there's going to be one hell of a price hike. Even more so because economic output is likely to go down.
Then in case the crisis gets really bad it'll turn out you can't eat cash. Nobody is going to hand over food or other useful things in exchange for a few bits of paper with questionable value.
This may be happening in some limited fashion even in the current crisis. My country still has its own currency within EU, and is undergoing unprecedented levels of lockdown over the last few days. The currency is already tanking compared to Euro (lost 4% over a few days), as people stockpile stuff.
(But being good to your family, having low or no debt and some prudent food storage are also wise, among other things our church has counseled us for a long time). (Edit: and savings "for a rainy day".)
(Edit: This is considering the definition of "cash" to be not just paper in your hand, but as a regulated currency whether paper or in a bank. Further clarification in another reply just below.)