There are no hard and fast rules about inviting mom to the bachelorette party. A bachelorette party is an opportunity to give the bride a well-deserved, entertaining distraction before the big day. The real key to understanding how to construct the event is in recognizing that keeping the bride upbeat, happy and lighthearted is the main goal. Her tastes, interests and wishes regarding guests should always take precedence over other considerations. Think of the bridal shower as the more formal gathering and the bachelorette party as the bride's own, unique and individual celebration.
Party specifics will vary depending on the temperament of the bride herself. If she relies on her mother and has a really close relationship with her, then it may be only natural to include her in the fun. There are a couple of exceptions here, though. Some bachelorette parties involve antics mom may not be comfortable with, and in these circumstances, she may feel fine sitting out on this one. In others, the mother of the bride's personal circumstances or the logistics of the party itself may make it difficult for her to attend, so practicality and sensitivity should play a role in the decision, too.
Before you start making reservations, there's something else to consider. Even though bachelorette party planners have the license to do just about anything they want, including chartering a plane to Vegas for a night of "What happens in Vegas . . .", if mom is included, then the mother of the groom should also be invited. It's the polite thing to do, and not including her would appear rude.
In some quarters, the bachelorette party is considered a "girls night out" anyway, where a multi-generational guest list would be less than ideal. Most moms and older relatives will understand your having one wedding event just for friends.
This sounds easy, but there are some potential gotchas involved. You may be in a position where mom expects to be part of everything associated with the wedding -- not adding her to the bachelorette party guest list could create hurt feelings. In cases like this, there may be a middle ground between inviting mom and not inviting her. Some brides opt for a luncheon, dinner, spa day or event at another polite venue that includes mom and then go out later for the bachelorette party, a more raucous and, well, adventurous gathering. If you can pull it off, it's a diplomatic solution that should work for everyone.
In the end, the bride's wishes are golden on this occasion, and ushering out those last rambunctious hours of singlehood in style and without undo worry are the real priority. This is a time to relax and cut loose before the big day. She should be able to have fun!