Is a rehearsal dinner mandatory?

We are having a food truck at FH's parents house and having coolers of beer and wine. Much cheaper and easier than taking everyone out to dinner

You need some kind of meal. My FMIL is considering hosting a dinner for just the BP, SOs, and our immediate families at her house. It doesn't have to be fancy or expensive.

We are getting married in a very small town so we were able to rent the downstairs of a bar on the marina for very cheap. We are doing lasagna and salads for 40 people costing us about $400 with a bartender. We were gonna do a barbecue but we found this option for much cheaper so it works well for us!

@FutureMrs and @Elizabeth I didn't mean ask them to host, I more meant it might be good for FH to say something along the lines of we're planning to do a pizza party as a rehearsal dinner, but I wanted to make sure you hadn't already planned something. They may have and not conveyed it or they may have planned to and been waiting for a go ahead. I assume they'd be invited to the rehearsal, so you'd need to tell them plans at some point. And if the relationship is that strained that they aren't even coming to the rehearsal/wedding, then that's a whole 'nother set of issues.