How much to give for a communion?

I know others might have asked this but I wasn't sure. We were invited to a 1st communion next month at a Country Club in Nassau County. It will be the four of us so I wasn't sure how much we should give. My sister said $50 would be good but my mom disagrees because they will be feeding the four of us. This is my father's cousin' grandson.
Thanks!

Although it doesn't sound as if you are very close with them, I'd still say at least $100. b/c there are 4 of you.