I have a family of 4. The eldest daughter went off the college and the youngest child was adopted when the parents were quite old, more than 50 years old. So i went to sleep and the next morning, the parents have passed away but i'm still able to play the youngest daughter who is now 16 years old. She is unable to work though.

I'm confused. Did the youngest child inherit the house automatically?

If you go to the family tree at the top center there should be a button that says something like "next generation", click it. That will take you to the screen to choose which kid to play as an "adult"

No, she did not inherit automatically. You can choose to click the next generation button on the family tree, or to allow her to stay in the house until she goes to college. If you choose to let her stay, as long as you have enough groceries or money to buy groceries, she will continue to age at the normal rate. If you choose the next generation button, the children all advance in age to be around the same age as your original adoptee was.

Ah i see. Thanks for quick reply. I was panicking a little since i really wanted to play the eldest daughter more.