What kind of care should parents provide to their child with single ventriuclar heart? between the fonton stages and after fonton rpocedure is done ?

Depends on the child: The questions to ask the child life people at the pediatric cardiology department, the surgeon, and the cardiologist, are "what are the restrictions for the child after recovering from surgery", and "how can a parent tell if the child is doing too much activity". They can confirm when and what prophylactic antibiotics are needed. It's a good idea to get vaccinated and avoid sick people with colds.