last month we (1).....so excited because we went on a vacation

--•Tobe past•--
Responsio :
(1) were

----------------------------
"We are addicted to our thoughts. We cannot change anything if we cannot change our thinking." -Santosh Kalwar

Last month we were so excited because we went on a vacation

Answer : were

This is past tense cause it happened in the past.
Past : Last month
Verb : went (verb 2) go (verb 1)

Past tense : subject + verb 2 + time

Example : I went to Malaysia Last summer