This is the kind of post that makes me figure--surely there's more to the relationship that this one issue, right? Is this a pattern with her, the tendency to be critical and to pick at you over something as small and dumb as "details" she can either wait to get or get for herself? Beyond this one instance, is she usually reliably "lazy and unappreciative"? These kinds of behaviors don't just crop up over one thing; they're there all the time, usually.
So if this IS unusual for her and she's usually more helpful, self-reliant, not critical -- I would say, have your husband talk to her and find out why she's acting out of character. She might be nervous about the trip; she might not like the idea of a huge gathering but be afraid to say so because it'll upset others; she might be having health issues she hasn't disclosed (and doesn't want to disclose for fear she'll be blamed if the trip doesn't go as planned). If this behavior's not normal for her, there may be other things going on that could explain it and you could then cut her some slack.
If this IS her normal way of handling things, well, then it's to be expected that she will nitpick and criticize so it shouldn't be a surprise to you or your husband either. Have him handle her from this point on, and only him. His parent, his job. Period. If she texts, you are not obliged to answer instantly. If she calls, screen calls and have him call back and say you're really busy our out, and "Mom, what can I do for you?" If she e-mails, that's great -- take a day and many deep breaths before you e-mail back. Don't let her think that contact equals immediate response and let your husband be the main point of contact with her.
Unless you want a really miserable trip, be sure to paste on a smile when you talk to her and keep repeating: "Husband gave you the number and e-mail for the rental agent. Hey, did you see X on TV...." or whatever you must to do change the topic. Every time.
Please heed Diane B.'s entire post. Don't put mom in your villa and don't try to organize the outings, the meals, etc. for everyone. You got them down there and got them housed. After that, be sure you and your immediate family have alone time at least once each day.