Best medicine for Ear mites?

Hello everyone! Summer is here and my babies go in the backyard occasionally (fenced in) and I wanted to know the best medicine to treat ear mites just in case.
I had purchased a bottle of medicine from Petco (clear bottle with a pointed nozzle) but it didn't work last year. Any advice would help! The picture below is my Boston Terrier Twiggy and one of my kitties, Orchid

Do you mean treat them just in case, meaning preventative, or to have on hand just in case they do get ear mites? As far as I am aware, there is no preventative medication for ear mites. There are treatments meds, but most safe and effective ones are prescribed by a vet. I am not aware of a safe and effective OTC one. Maybe some other members will have some suggestions for you.

Oh, and adorable picture of your furbabies by the way! Welcome to TCS.

Are you in the US?  If so, Revolution treats for fleas, worms, and ear mites.
 

Revolution hands down. Cleared up kitten within days, and with only one topical dose

plus it does fleas, ticks and roundworm