Vow renewals do not require a gift. Period. If someone wants to gift, great, but it's not a Ms. Manners obligation. I know, I went to a vow renewal not too long ago and looked into it. I did gift them but that is because I wanted to and I found something that had them written all over it.

I don't have a suggestion on attendance. It's a mixed bag in my mind. Going or not going. By virtue of your husband. Going supports him. But if he supports you staying home and going by himself then so long as it doesn't make waves between the two of you then do what feels best.