Can I claim my son on 2019 taxes

My son who is 2 was on someone else’s Medicaid the whole entire year. But he lived with me most of the year. I had a family friend help me out a lot and would take him to the dr for me while I was at work. I have custody but this family friend is telling me they are claiming him as their dependent this year. I’ve read the qualifying child requirements and my son is not related to this family friend. Can he still claim my son?