How many and what type of Adaptor plugs for airbnbs inItaly

You need phone chargers that can hold 3 phones. They are cheap so buy some ready for Italian outlets.
Use Booking.com to find a hotel because they have good filters and maps for searches. They also have real user reviews so you should read many of them.
This article explains electric adapters: https://www.marthasitaly.com/articles/85/plug-adapters-for-italian-outlets

These have worked for me https://store.ricksteves.com/products/european-power-adapter?variant=46194368774300

Just bring the charger you use at home and an adapter for each charger like the one Mary linked. You can also buy them from Amazon or Walmart or wherever.

Type C (https://a.co/d/06G7A8NI)

If your appliance has 3 prongs (with ground), then I recommend to buy also one Type L (https://a.co/d/0eDj9uyc).

There are also adapters that have multiple sockets and USB ports. Those are useful for multiple devices as the available sockets in hotels may be few.

If you or anybody in your party has a CPAP machine, be aware that the socket may not be available near the bed, so you need also an extension cord.

I’ve always used the RS single plug adapters since they weigh nothing and are cheap. Same one Mary linked:
https://store.ricksteves.com/products/european-power-adapter?variant=46194368774300

Traveling solo, I usually take three adapters: one for my phone charger, one for my multi port/plug extension cord and one for power block chargers. One adapter will be forgotten in a socket somewhere in a hotel.

I don’t take a notebook or laptop. Hotels have hair dryers. Only you and your travel group will know how many you need depending how much tech you take and how willing you are to share.

Be aware that some older hotels and B&Bs do not have many outlets and the outlets may be behind furniture.

Italy can be a bit more complicated. Three types of plugs. C, F and L. See https://www.worldstandards.eu/electricity/plug-voltage-by-country/

In 2024, it took us nearly 30 days to get to the third type that we needed - and had not brought with us. And that hotel (in Naples) on our last stay that month did not have an adapter (perhaps it was L to C) that we could borrow, so we had to find a shop to buy one.

As you may well know, many devices, eg cell phones and laptop computers, do not require voltage converters. Some do, eg waterpick and perhaps electric toothbrushes. Definitely hairdryers, but why take one when so many places have them for you.

The Schuko plug (Type F) in Italy is used practically only for domestic kitchen appliances such as refrigerators, kitchen stoves, microwave stoves, dish washers, and also for washing/drying machines (which in Italy are often in the kitchen or in the bathroom of your AirBnB). That is where I have it also at my house, in the kitchen. It became prevalent for those large domestic appliances with the advent of German appliances in Italy a few decades ago, especially Siemens products. It is however rare to see it for any other outlets other than kitchen and wash/dryer appliances, so I doubt it you will need it in any hotel room or bedroom. Take type C only, and maybe type L (see my link in my previous comment above) but only if the cord of your device has 3 prongs, otherwise it is not needed. If the Italian socket has 3 parallel holes, it will still take the type C, which only has 2 prongs.
I am also sure that your AirBnB host will provide you with a Schuko to Type C/L adapter. I don't know of any Italian household that doesn't have a bunch.

We stayed in private apartments through Booking.com in Italy several years ago. I brought 2 types of C plugs, the older one had slightly smaller circumference plugs. We needed the smaller plug for the older apartments that hadn’t updated the electrical wiring. The larger circumference plugs fit the more modern apartments. Glad I brought both adapters. It sure surprised me. Can anyone explain the size differences?

Type F has larger circumference prongs (= prongs in type F are fatter).

Type C all have the same circumference prongs.

Type F are used for larger domestic appliances, like fridge, stoves, washing machines, dishwashers.

Type C is what you have everywhere else.

This is what I take on all Italian trips, for two people traveling with: 1 laptop, 1 tablet, 1 phone, electric toothbrush.

https://www.amazon.com/dp/B07WRWX15J?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_3&th=1

I take that smaller one, linked above, to use for electric toothbrush in the bathroom.

The 3 people I your group: Are they each taking laptops and phones???

Something to bear in mind - trains in Italy with outlets (and some older hotels and apartments) have outlets that only fit the smaller size C in the link below. The big, round ones don't fit, which I learned the hard way.

https://www.worldstandards.eu/electricity/plugs-and-sockets/c/