Water, witch hazel (if you're getting generic make sure to read cause its usually more percentage of alcohol than WH) melted coconut oil, a couple drops of tea tree oil depending on how strong yours is. Your dogs ears will smell good too!
For Elly. Best thing I have ever used on my dogs ears for a yeast infection! It worked in 2 days . We were applying medicine from the vet for over 3 months and it never got better, constantly getting worse.