I usually have earplugs in my possibles bag. Whenever I have to officiate a wedding, I pretty much know I will need them for the party afterwards. Our Middle Eastern families like to have über-loud music at their parties, and after a few sleepless nights with tinnitus I started carrying earplugs.
Headphones, however, might not help, unless companies start renting them 400 at a time.
The last wedding I was at, I actually forgot my earplugs and ran across the street from the church to a pharmacy and bought a bag of them. By the end of the evening, I had handed them all out!