Where did Khushi go with her mother, and why was she happy? (Understanding)

Khushi wakes up hearing birds chirping.

Khushi said this because Rupa had a stomach pain. Drinking dirty water or not drinking enough pure water can make people sick. Khushi wanted her friend to stay healthy and avoid pain next time.

Khushi is happy because she will go to her grandfather's home. There she will meet with her friends.

I should brush my teeth after breakfast and dinner. I should take my bath everyday. Also I must drink plenty of pure water.

Pure water keeps my body fit and healthy. It helps me to get free from stomach pain.

Khushi saw many trees, golden paddy field, blue sky on her way to Kusumpur.