Help with selling a tax sell house in PA

[Caring Housely]

So I recently got a house from the tax sell/ foreclosure auction  in PA and someone reached out with an offer to buy it. I spoke to a  real estate agent friend and they said that I will need the social security number of the previous owner to sell or list the real estate that I got at the sale. Does anyone have any idea how I can get the social security information of the previous owner if they are deceased and they have no relatives.