How to correct past mistakes

Hi,

I have been transferring my additional savings in my mother's bank account since last 5-6 years. 

I did fix deposits of those amount on my mother's name on which she got interest.

My mother is a house wife and senior citizen and is in 0% tax bracket.

I did not file her ITR and not shown interest income even in my ITR.

Now I am worried and want to correct my mistake.

How can I do it and how much penalty I need to pay?  

Please help.

Thanks in advance.