Q. Must a person always go to events they are invited to? Respond from Hadith please

A. It is sunnah to accept invitations. Rasulullah (sallallaahu alayhi wa sallam) accepted invitations. Proof exists that he sometimes made conditions that made His presence welcoming. He (sallallaahu alayhi wa sallam) also went to the house of his daughter, stood by the door, and thereafter left without attending to the given meal in the house of His son-in-law. (a reason for this does exist, see miskaat sharif)

Thus we learn, although one should not refuse an invitation without a valid reason, an acceptance does not mean that one has to attend the entire event, meal, etc. All an invitation means is that a person accepts on condition that they can be present.

The host must not force a person to attend. The host has the right to invite, just as the guest has the right to attend.

Should the host invite a specific person, and in guests honor the event is being held, then the person should attend so as to not embarrass the host. Should the guest decide not to attend,  then is such a situation the guest should make it known before arrangements are made that they would not be present.

Allah Certainly Knows Best.