as your baby is too young i would suggest you wait about the mustard oil treatment (though you can definitely start doing this once your baby is about 1 and half).
in the meanwhile, take a soft cloth and slightly wet it to make it damp. use this to wipe your baby's ears - the outer areas. once a week, you can use baby oil to clean the outer areas of the ear, the areas that are easily visible. avoid inserting anything in the ear drum area.