It is advisable not to go with any oiling methods to clean your baby's ear unless its prescribed by a doctor. Mild to moderate earwax build-up is common in babies. I usually wet a soft washcloth in warm water and use it to clean the earwax that's collected around my baby's outer ear. Also, don't push the cloth inside the ear. Most of the time, any earwax that is visible will fall out on it’s own. Ears have the ability to dump off the earwax accumulated within the duct and this process usually takes place when we sleep. So there is no need of pouring oil to dissolve the earwax.
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.
I wouldn't suggest mustard oil to clean your child's ear. Many times the moisture that doesn't get cleared well, causes a fungal infection in the ear. Best is to use a soft cloth to try and clean the ear. Avoid cotton buds as well till your child is older.
I haven't heard of this. How does this actually work?