That depends on the question! I shall guess that you are asking which option you would use in the situation of a guest leaving a halloween party. A) - My pleasure. I am glad that you enjoyed the party, it was beneficial to/enjoyable for me to have hosted it. B) - I'm glad to hear it. I am happy to hear that you liked my party. C) - No, thanks. I am refusing something (but you are not offering anything so this cannot be the right answer) D) - It is ok. I'm not that bothered but I am accepting your thanks anyway. Alternatively I disagree and I think the party is only ok and not wonderful. If a person used B or D, I would think that they were being a little rude. I am complementing their party and they should recipricate the good feeling. B can be seen as a little threatening "I'm GLAD to hear it" - they are not really all that glad. D would indicate that the host feels that s/he has made a sacrifice or has lost out in some way by hosting the party. You should say A my pleasure. It is more courteous. You are accepting the complement but in a way that makes the guest feel that he has not caused any trouble or inconvenience to the host.

It's been a wonderful Halloween Party.Thank you very much. It's my pleasure. (We say this expression to show gratitude to the other person's compliment.) It's been a wonderful Halloween Party.Thank you very much. I'm glad to hear that. (This is also possible because it shows agreement to what the other person said.)