Is dht produced by masturbation? Or there is some other reason as well? How we can stop it without drugs to get better growth of hair?

No worries. If masturbation (think of it as: sex without another person there) causes hormonal problems, then "sex with another person there" would cause the same hormonal problems. If one were to avoid masturbation (due to worries about losing hair), it would also mean avoiding "sex with another person" (as one should have the same worries in that situation). Thus, no worries. Live life.