Itchy ears but no coffee grounds debris

Two of our cats have very itchy ears. They are going to the vet on Monday. They don't have the typical coffee grounds debris seen with ear mites, so I'm thinking maybe yeast infection? There ears just seem dry and a little scaley. Any suggestions to soothe their poor little ears until Monday. Vet suggested a couple drops of mineral oil, so am going to try that. Also we have a couple of neighborhood strays who I see scratching the same way. I'm hoping the meds for this are affordable so I can treat them too. They look miserable.