We need to know whether the people having the conversation are at the party or not. It will affect both the question and the answer. IF THEY ARE AT THE PARTY: Is your wife coming to the party tonight? Yes, She is here already. (Party) IF THEY ARE NOT AT THE PARTY: Is your wife going to the party tonight? Yes, she is there already.(Party)

"yes" is odd in both answers

No, they’re not. The first answer implies the two speakers are in the party at that point. On the other hand, they are somewhere not in the party according to the second one.

Please, help me too