My mother is 57 year old she has a lump on her inner right ankle which is painless. it was very small in start but grew. she can even walk without feeling any pain. its firm to touch. and very visible. is is something serious im very stressed?

I assume the ankle isn't deformed from an old fracture. A physician should examine her ankle and most likely will order an X-Ray for thorough evaluation. The lump could be a bone spur, but concern would be for a bone tumor.

My philosophy is all lumps, bumps or anything else should be seen and evaluated. To guess what a mass can be is risky. The chances are it can be benign but you will not for sure. Could also be a mass associated to the flexor tendon sheath . In other words have it examined. Guessing is a fools game.