Like it or not, she's apparently close enough with your ILs to be included. The only time I think it's appropriate to ask that someone not be included is if you've had a major falling out, you've completely cut ties, and it's widely known that you refuse to associate with her. Otherwise, it's just in poor taste to ask that she not be included in your shower.
This. Plus, your MIL is hosting the shower, so really it is up to her to give the final say on the guest list. To ask her to not invite someone would be rude.