Okay so I'm writing this at 9:30 PM on Friday night. So let's assume you see this on Saturday morning at best. That doesn't give you a whole lot of time man. Your mom... she might understand. She's older and has probably had to live through some disappointing mother's days already. But your wife? The mother of YOUR children? Yeah, you better think fast. You need some guidance. You need a very, very last minute Mother's Day gift guide.
Unfortunately, you don't have the luxury of getting something off the internet with this time frame. So that rules out something like that cute dress from Mod Cloth that you've seen your wife checking out online on multiple occasions (which is what I got my wife BTW). And it rules out anything that you could lazily pick up off of her Amazon wish list, though you could go find something that was wish listed and buy it at a brick and mortar store.
There are certainly some hot trends right now that you could look to as an option. Adult coloring books are all the rage these days. Try picking out a couple and adding in some high quality colored pencils. Package it all with a few colored pages done by your kid/s and you're good to go.
While I have bought purses for my wife in the past, it can be a risky venture and you need to be really sure that you know your wife's taste spot on. A much less risky option would be to get her a fashionable and functional back pack. Depending on what your wife is like and what she is into, she may already have a Herschel backpack or might be coveting one. These are very well made backpacks that also happen to have become part of the "hipster" aesthetic.
Classics are classics for a reason right? You're on a deadline now but you can be saved by the old standbys of wine, chocolate, flowers, etc. Of course, personalize the heck out of it. Don't come with some sad box of Russel Stovers and an even sadder box of Franzia. You better have her favorite type of flowers, some fancy salted caramels and a wine that runs at least $15. Hey, this might actually be what she wanted all along.
Oh, last thing. Above all else just be nice. Treat your mom and your wife like the wonderful women they are. Attend to them, don't let your kids bother them, give them time to rest and enjoy their one day. If it helps you to think of it this way, remember that Father's day is right around the corner.