What did the doctor suggest? I would definitely go with what your doctor suggested. If it's right for you. I'm sorry for your loss.
I had an incomplete miscarriage and hadn't delivered the entire m/c he suggested a d and c and for me it was easier then hoping the placenta and rest of the m/c would eventually delivery on its own. But everyone has to do what's right and best for themselves.
If it has only been a short time, let nature take its course. But after a couple of weeks, you run the risk of getting scar tissue that can interfere with future pregnancies. If a couple of weeks have gone by and you haven't passed the tissue, go for the D&C to prevent that risk.
You could give your body a chance to expel the baby on it's own. If nothing happens, then you'll have to get the d&c.