The tigers that An mentioned are Jade Guardians, and they can be found all over the Forest Heart.  For the most part, these are typical cat enemies, with Rake attacks and all, but they do in fact have a stare attack that turns you to jade.  However, it’s just a snare, and the jading only incapacitates you for a few seconds.  Damaging, but hardly fatal.  Better yet, it’s a slow-casting effect, so a stun or interrupt during its (six to eight second) casting bar will prevent your being snared entirely.

The Scared Pandaren can be found clinging to various bamboo shafts, a short distance off the ground- all you need do to rescue them is talk to them.

Once you’ve rescued enough cubs and slain enough jade tigers, talk to An, who has followed you into the Forest Heart.  She tells you that she’s very grateful, and gives you the ring you’ve been promised, but she hasn’t seen Shin anywhere- so clearly the Jade Witch must still have him.  An can’t stand the idea of going to see the witch, so she asks that you go talk to the Witch and find out if she has Shin- after all, you’re an adult, surely she won’t try to turn you into jade?

The Widow Greenpaw is waiting in the entrance to her hut, with a couple of animated jade cats wandering around her.  When you talk to the Jade Witch, she asks if you’ve come to pay your respects to her husband- a master of Jade crafting and Jade fighting, said to be remembered forever.  She also asks if you like her statues- she claims she uses special care on them and saves only the best to give her husband ‘company and protection’.

When you ask her where Shin is, she takes you out to the back of her hut, claiming she heard ‘some young whipper-snapper’ back there recently.  Once she has you in the back near the statue of her husband, she points out Shin- one of the statues- and says she and her husband both wanted children.  In fact, she’d like to add you to her eternal family too!

The Jade Witch isn’t a hard fight, really- while the Widow Greenpaw does have several ranged attacks that involve throwing jade, one that will knock you back several meters, and the ability to summon one of her jade cats to help her, she neither packs a remarkable punch nor immense wad of health, and her damage (while nothing to sneeze at) isn’t terribly dangerous as single enemies go.

When you slay her, all the statues on the ground around the memorial to her husband come back to life- including Shin.  An greets Shin happily, and then runs back to Dawn’s Blossom, promising that she’ll give you something the children picked up on their adventures if you go talk to her.