Should you drink 6 glasses of water & 2 glasses of milk or 8 glasses of water only or 8 glasses of water & 2 glasses of ?is "6 glasses of water & 2 glasses of milk" considered as hydration?which option is the best for height growth for teen?(growing?

Neither. I consider counting glasses a waste of effort. You need to take in enough fluid value/day to pee every 6 hrs as a good reflection of normal hydration. Take in too much & you waste time/day voiding. Many fleshy vegetables are 60% water and add significant fluid value. Normal hydration supports normal height.

Drink enough water daily so that your urine is mostly colorless. Drink milk as you like. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV, Flu and Covid vaccines. Wish you good health!