Considering it is at their home, and you are kind of hijacking their party, make it easy to put together, and easy to clean up.
Dollar stores are great for serving platters. I’d tell everyone to plate their own food and bring a disposable serving utensil as well. Bring some “nice” plastic serving ware, you know the faux silverware and faux china. Maybe a couple table cloths and ribbons to tie around the legs, but see how they have everything set up before you pull these out, they might not be necessary
Since it also a housewarming, maybe some nice potted plants for decorations. If you bring candles, bring matches, don’t assume they will have anything. Gifts, music, a portable speaker if you have one. That should be plenty.