There are alot of places to take kids.
Firstly take them to lodhi garden, Humayun's tomb and wonders out of waste park to have the best of Delhi history,
Take an evening stroll in qutub minar area.
Go to red fort and old Delhi area for a nice eating out day.
Can also go to ambience mall vasant kunj it has gaming area and VR games.
Would be really fun for kids