Mnemonic restoreNnemo = new Mnemonic("Тут сид фраза");
ExtKey masterKey = restoreNnemo.DeriveExtKey();
KeyPath keypth = new KeyPath("m/44'/0'/0'/0/0");
ExtKey key = masterKey.Derive(keypth);
string ssAddress = key.PrivateKey.PubKey.GetAddress(ScriptPubKeyType.Legacy, Network.Main).ToString();
MessageBox.Show(ssAddress);