Anybody (over 21) can pick up a bottle of wine from the store to bring to a party. But you can get creative and find or make great gifts that your hosts will treasure for longer than it takes to drink a bottle of wine. Make the gift useful, or so beautiful it doesn't matter that it's not useful. And never give a gift you wouldn't also like to receive. Make sure you stock up on a few gifts at a time so that you do not have to run out at the last minute or resort to giving an alcoholic beverage.
Look for unique gifts - try vintage shops for a nifty wall hook, a beautiful set of table linens, or a cool old container in which you can transport a homemade element of your host(ess) gift.
Go homemade, and theme the gift.
For example, as a housewarming gift, find an old wire or canvas basket, an old enamel or zinc wash tub, or a big wicker basket that could be used as a laundry receptacle, and fill it with homemade laundry detergent, wool dryer balls, essential oils, and homemade laundry softener. Add a few wire hangers wrapped in scrap fabric.
If your host(ess) is a baker, fill an old bread box or cooking utensil canister with a kitchen towel, a wooden spoon, and some homemade vanilla extract or homemade jam.
If they prefer a good cup of tea, prettily package up a cool old tea kettle, a couple of mugs, and a jar of their favorite loose leaf tea.
When all else fails, go get that bottle of fine (biodynamic) wine from the store. They probably won't complain.