What should I do about frequent wet dreams, sometimes involving seeing my mother, and the sadness this causes?

No one is held accountable for a wet dream (emission of semen during sleep) because it occurs unintentionally and during sleep, and a sleeping person is not held responsible. The pen has been lifted from three: the sleeper until he awakens, the afflicted until he recovers, and the child until he grows up. Therefore, there is no sin in it, and no need for sadness.