As you'll be ground-side having cleared Immigration/Customs you'll need to get between terminals on the monorail and the clear the security line into Terminal C. It's that last bit that would really concern me, those security lines can be long. Also C itself long, you could have a bit of trek to the gate.
Given that you need to be at your departure gate some time before the scheduled departure that 55 min window is rather less, so I would consider 55 min to be unreasonably tight.
However, I'm very conservative when going through EWR, and in previous discussions on this kind of topics people who know how airlines operate have assured me that if the connection is scheduled then it's feasible. One positive factor is that the airlines know that there is some slack in scheduled arrival times, so on a typical day you may in reality have more than 55 min.
If this is a single booking with a single airline then I could assume that they will deal with any issue if I miss the connection, it would be hassle, but I'd get there in the end.
If this is two separate bookings then I would be concerned as the risk is entirely yours.