Is there no any therapy to treat or to minimize the after effects left by bacterial meningitis? like some cognition problem, clumsiness, mood swings...

Mennigitis: Yes there is therapy usually done through a neuropsychologist. Check with a neuro-rehab facility they should be able to direct you.

Some but specialized: The primary damage to nerves caused by scarring from the infection is likely permanent. Nerve cells are slow to regenerate or re-connect. That said, a comprehensive assessment of strong & weak areas of function allows a therapist to teach to the strong areas and avoid the weak. Rehabilitation centers employ these methods to improve function & limit long term impairment.