My parents only income is the social security from Germany, therefore they don't receive a 1099 here, on which line should they report their income?

In past years they always reported it under  line #20a social security benefits.

But this years form is different and when we went through the process we had to fill out a form which we don't have 1099. 

The federal return was accepted but the state was rejected because of that form.

Not sure what to do?