The only workable system there is barter. The money will lose some value by the next day, but the items value (relative to one another) will remain constant. A chicken for four loaves of bread, a bag of onions for a liter of beer, you get the picture.
Hopefully those poor folks have enough things to trade to keep body and soul together!
Barter will only work for smaller things. You can’t trade onions for electricity. The cities are poised to collapse back to pre-industrial times, and there’s nothing Mugabe’s “war veterans” can do about it except to set up their own little medieval fiefdoms. Mugabe won’t realize this until the mobs start trading HIS stuff. No hope now, even if South Africa and other neighbors decide to remove him.