The SS doesn't matter. Is he claiming you also? If you all lived with him the whole year and you had less than $4,400 income for the year he can claim you and the kids. Their SS doesn't count towards the 4,400. But he can't claim Head of Household unless he has a child of his own.
Who can you claim
https://ttlc.intuit.com/community/credits-and-deductions/help/who-can-i-claim-as-my-dependent/01/267...
FOR SOCIAL SECURITY
You don't include their income on your return. It would only go on their return if they are required to file one. If they only got Social Security or SSDI or ssi they don’t have to file a return and nobody reports it.
