My wife eats a lot after after a long day of taking care of our baby. Is it normal?

Your wife is working hard taking care of the baby and breastfeeding! Rather than focus on how much she eats, I'd be more concerned with being there for her and being supportive. If your wife has expressed a concern for eating too much, then I'd try and refocus her food to more vegetables and foods high in good fats such as sweet potato and avacado which are filling but healthy.