Yes - firstly at the funeral, and then I think they were both at the 65th party in 2011, but I can't be sure. Whether they socialised together at that party I've no idea.
Paul Gambaccini said he had „that sinking feeling again“ when when he asked Mary if she had changed her behavior towards Freddie's relatives after she had taken over Garden Lodge. With her usual arm flourishes, she answered „fuck anyone else, darling. I am doing whatever I want with everybody“. Needless to say, Gambaccini subsequently had that sinking feeling once more.
On a brighter note, no one knows whether Freddie's mother every wanted to see Mary again. Austin was never to be seen at any of the many official receptions, was she? Even Freddie's seemingly disabled father went to Montreux for the induction of the statue and to the opening of the FM-photo-exhibition. But Austin was never to be seen again. What would she have talked about with Freddie's mother anyway? The good old days, when she was playing a huge part in Freddie's awful pretense of being straight?