What you do has already been explained above. You just file a paper return instead of an electronic one.
But, If social security is your only income, you do not need to file a tax return, at all, and will get no benefit from claiming kids.
The money you hear about people getting for just filing a tax return claiming kids requires you to have some earned income (wages or self employment). Without earned income, you are not eligible for the "refundable" Earned Income Credit or Additional Child Tax Credit.
