Ask an Immigration Solicitor. Get an Answer ASAP.
i can help you for your concerns.
you will have to prove that your mother is financially dependant on you. No one is available to take care of her.
I am afraid, no other option which you can use to bring her.
I hope it will help you
please give positive rating
1: you will have to prove that she is financially dependant on you in Sri Lanka. you send money on regular basis for living expenses. she is the house hold member in your house in Sri Lanka
2: No other family member ia available in Sri Lanka to live with her and look after her