I strongly feel that you should help your parents under any circumstances. It should not matter whether you have the funds or not. Your parents never thought about funds.
If they had less funds, they somehow managed to provide you a meal even if they had to stay hungry! So, I think you owe a lot to your parents and you can only try your best to help your parents (You will never be able to match what your parents had done for you).
I know it doesn't sound'Practical', but if you will give it a deep thought, you will realise it yourself.
