No, never use hydrogen peroxide in their ears.
I use it, diluted, on my daughter's pug, about once a week.
If you want to be extra safe, just use vinegar/water solution. I use the vinegar solution twice a week.
I also use vinegar and water in a spray bottle as a leave-in rinse before towel drying (twice a week bath). Vinegar is a wonderful chemical. It disinfects, it resets the pH, and it is an astringent which helps dry her out, which discourages fungal growth.
That dog has gone from being a smelly, oozy, nasty little beast who would scratch herself to bleeding to being a luxuriously fluffy, clean dog in two months of Jeff Chandler dog therapy. People actually like to pet her now, her ears are clean and no longer stink, and she hardly itches at all.
Oh, and daily fish oil pills have helped eliminate the allergy inflammations, too. Omega 3, you know.