Note that this question seems to have been asked in three different variations with responses to each of the three.
As explained, Rick's USD emergency cash advice is intended as an emergency bridge to resolving your ATM cash problem should your ATM card fail to work in Italy. Italy seems to be more cash oriented than countries like Switzerland or Scandinavia where credit cards are the normal form of payment. That said, if your big expenses (hotels) are pre-paid or payable by credit card, your daily cash needs are more for cafes and dining. In that case, $200 USD converted to EUR at a FX kiosk rate could be adequate for two or three days of small cash purchases.
On the other hand, if you need to pay cash (Euros) for lodging, you should have back up ATM cards and accounts or a trusted form of obtaining Euros.