What rights do fathers have?

[Redregine]

My mother had custody of my son because DSS took him from my ex-wife. Now she is trying to get him back after 7 years of living with my mother. He is settled and happy and I see him daily. I don't have money for an attorney, and have to pay for the court evaluation. What rights do I have to not have to pay for it since she is the one that filed, and how can I get an affordable attorney in NC?