So sorry you and dh are going through this, Dotty. Agree with the others that you need to stand up for yourselves. Sadly, dd may be doing this just because she can. This needs to change.
Perhaps take a preemptive strike? Let her know you can't childmind anymore if she doesn't treat you better? You would have to be prepared that this might backfire though. She might find someone else to watch gd - might even be willing to pay for childcare if she gets angry enough. Probably not though, so may be worth the risk.
But Yogagirl has a point, imo, about dd maybe being upset that she doesn't have more time with gd. Perhaps she's jealous of the activities you get to do with her and needs to hear LESS about them? Or the opposite - maybe ask her if she would like you to videotape some of it to show her. Maybe that would make her feel more a part of gd's life? But if she declines the video idea, then don't, of course.
Also, is there a pattern to the things she finds fault with? Do you tend to bend her rules for gd? Does dd think you give into the child too much or are too strict? If you spend some of your childminding time in dd's house, do you take off your shoes if that's her rule? Do you used dishes she has asked you not to? (These are just examples, I'm not saying any of them are actually the issue.) You say you "jump" if she says so, but do you observe her rules for her home and her child when she's not there?
If you find a pattern to her complaints, then maybe you can change your behavior to ease the tension. But if not, then, imo, you do need to take that stand.
What do you think would go well with coasters like this?