The so called dent over the forehead is nothing to worry, as it has been there for about one year and your grandmother has no symptoms because of it.
It is possible that it developed after the injury
, due to depressed skull bone fracture
and has got spontaneously healed.
You may get a skull X-ray done for evaluation and show her to a neurologist/neurosurgeon.
Dr Sudhir Kumar MD DM (Neurology)
Senior Consultant Neurologist