Is this necessary to take home Tution for those students, whom mother and father both are working?

Is Only school  not enough for those students?

It depends more on the student and the teachers teaching in the class. If he's regular and can understand in the class and clear all goo doubts and give time to the subject them he doesn't need tutors. But if he doesn't have extra material to practice from , then definitely he needs some guidance from outer source.

Depends completely on your parenting. From the first day of the session if you can spare half an hour per day ( for smaller classes ) to an hour or two for bigger classes with your kid and help him learn and understand the subject the way he/she needs it then there is no compulsion for tutions. But if your schedule is too hectic or you are not confident enough to clear their doubts and help them learn then tutions are a better option. I dont encourage tutions at students home as they dont allow your kids to come out of their comfort zone. Coming out and attending group classes creates anxiety to learn and to compete with fellow mates. Even they can learn what new other school students from their class are learning and even share what new they have learnt.

only school is enough.. just monitor students' home work..student must complete school homework with continuity. If student is avg performer in school then no need of tuition at all. Tuition is required for underperforming student or the one who wants to prepare for competitive exam like NTSE, Olympiads, KVPY, NSEJS etc

First of all it depends on your child, whether he/she is good in self study and doesn't need home  tuitions . 

And second, since both of you are working and you can not give the adequate time and attention to your children due to your busy schedule and later the household chores.

so I recommend you to send your children to take home tuitions since schools are merely for business rather than the education.