I personally think Yang lady is YG's decendent. Afterall, she did say that quotation that confused ZWJ. She said something like about the mountain where All True Sect use to be and Seng Diao Xian Lu stuff, I can't remember! But there was a quick mention that gave us some hint.
If they were to fight, I'll put my money on ZWJ. Even if 9 Yin is par with 9 Yang internally as some of you guys say, 9 Yang training wise is no doubt faster. When ZWJ looked at 9 Yin, he said that if one was to spend 10 or 20 years then their kung fu would be incredible. As we all agree, ZWJ's internal was already omega GJ at 56. And GJ mainly practiced the internal for 9 Yin. One can argue that GJ is much more busier than ZWJ who just spent a lot of the day training. But GJ after 30 years should have surpassed 5 years of straight training. So even so, ZWJ's internal should surpass Yang Lady. And ZWJ also has the advantage with QKDLY which can be used to CREATE weaknesses in other people's attacks. I just read HSDS yesterday, QKDLY can move a technique and create a weakness that is attackable. When ZWJ say his grandfather fighting with Wudang 1, he thought they were holding back because he saw so many weaknesses, but in reality, the two weren't holding back. JY then says from 3rd view that there actually weren't weaknesses, it's just that QKDLY CAN MAKE THOSE WEAKNESSES. So I can imagine Yang Lady's external kung fu getting messed up.