@Patricia5066
Unless your listings are in an HOA that limits the age of residents (like an over 55 community) you cannot put limits or conditions on the age of the renter, as Airbnb views that as discrimination and it is against their terms of service. Your listing can be suspended for that. Here is a link to another Host with an age restriction whose listing was suspended:
https://community.withairbnb.com/t5/Ask-about-your-listing/AirBnB-Unlisted-due-to-Airbnb-s-Nondiscri...

Non Discrimination Policy
https://www.airbnb.com/help/article/2867
There are other things you can do:
1. You can require all guests to create an Airbnb profile and have the primary renter add them to the reservation details so you have their names.
2. You can add to your addl House Rules that parties are strictly prohibited and that unregistered guests are not permitted. Violation of these rules is grounds for cancellation of the stay, guests must leave premises and no refund will be offered.
3. You can add noise monitors (properly disclosed) on the listing and ensure you have exterior cameras (also properly disclosed). Minut has some good noise monitors and combo cigarette smoke detectors that you can monitor in an App on your phone.
4. Message the booking guest and advise them to state they have read, understood and will comply with all the house rules and so will the addl guests on the reservation.
BTW, Vrbo does allow you to put an age limit on the listing.