2:40 PM PT -- Here's photo evidence that Britney and her mother's relationship is repairing itself right before our eyes ... 'cause Mama Bear was indeed at her daughter's birthday shindig, and apparently spent the night as well.
These pics were taken Saturday, which show Brit leaving her manager's house in the L.A. area ... and wouldn't you know it, Lynne Spears is back there seeing her kid off as she hit the town in a waiting SUV.
You can see Britney saying bye to Cade as he escorts her to the vehicle ... and very clearly in the background -- you can see her mom, looking on. We'd already been told Lynne was in attendance the night prior ... so to see her there the next day is quite telling.
At 2 AM, Britney, Cade and Bryan left Cade's home and got in a car. An agency photog at the scene says she had her dog in the car and they rushed to a 24-hour veterinary clinic. We never see the dog, but the photog claims they brought it in.
Britney and crew then went to a gas station convenience store on the Sunset Strip, and from the photos you can tell this was some sort of emergency. Cade is in his PJs with no shoes.