Wow, some of you guys are awfully harsh to the OP. Its interesting to see so many people automatically assuming that the OP must obviously be so in the wrong for her daughter to snap at her like she did. So judging on a few posts, she is overmothering, treating her daughters house like a bed and breakfast, and overstepping her bounds.
First off, if her daughter has a problem with her mother staying with her overnight every six weeks or so, then the daughter should tell her parents that before they make the next trip down. The OP explained that the son has a smaller house than the daughter. Maybe he doesn't have a spare room for the parents whereas the daughter does. Regardless, the daughter should not open her home if she doesn't want them there. If the daugher always says its okay, how are the parents to know otherwise?
Second, maybe the OP was simply just trying to do a nice thing and make coffee for her daugher so that it would ready in the morning. Nothing more, nothing less. Funny how some people can take a simple gesture like making coffee and make someone seem like they have committed a great sin against their child by overstepping (no good deed goes unpunished I guess).
The daugher accuses of her asking too many questions, etc. Well, maybe she's just interested in her daughters life. It is quite possible that maybe the daughter feels like the mom is being "nosy" or getting too involved and the mom just doesn't realize that. I know people like that. They don't mean any harm and they don't realize that they are getting too involved. Again though, the daughter should approach it in a better manner.
It sounds to me like the OP and her husband have done a lot for their daughter, including buying the house. Some would consider that a good deed on the part of the parents. Others on here act like they did it to lord it over the daugthers head for the rest of her life (which the OP never makes it appear this way). Maybe the daugher does feel awkward about that and feels obligated to let them stay there. Again, a conversation that should be brought up by her at the appropriate time.
Snapping her mom's head off late at night because she didn't make coffee to her exact specifications and then listing all of her grievances right then and there is not the right time or place. Late at night, people are tired, stressed from the day, and everyone is more emotional. If this is out of character for the daughter, then I can see why the OP is so upset and crying. It hurts your heart when someone you love treats you that way especially when you were most likely just trying to do something nice.
I'm just amazed (although I shouldn't be considering other threads on the disboard) at how harsh some of you are. If I was one of your parents, I'd be afraid to walk into your house for fear of being put into my place.
To the OP, I really truly hope that you are moving on from this and it doesn't hurt your relationship with your daughter. I think that a good heart to heart with her might be due. But, please don't let the people here make you feel like you were in the wrong and make you feel bad.
For the record....I'm the daughter's age and I am very thankful to have a Mom that I love and appreciate very much.