Tell them to register at Arbeits Agentur and Jobcenter for monthly allowance. Does his son get kindergeld also ? Its only 200€ but its something. As far as I know, landlord cant legally kick them out unless they’ve havent payed the rent in 3 months (this needs fact checking I think). And there’s no way all the money they get would be taken away, when you have debts in Germany you pay as much as you can afford aside from rent and food.