If they do continue reaching out to me and my child, what could happen, or are there any steps I could take to be prepared?

My son's father has never met him. He's almost one and recently his mom (my son’s grandma) reached out to me randomly. I didn't even know she knew about him. I've given his father two chances to meet him since he was born but he didn't show up for either. He's never paid any child support and isn't on the birth certificate. I don't want my son around them because they abuse their prescriptions and do other recreational drugs as well. Their house is like hoarders; a filthy mess/gross and they also have 12 cats I that gives you a good visual. I'm worried about her reaching out to me. I don't want him around them at all. Should I talk to a lawyer in case they continue?