This page of the guide to Poppy Playtime contains a walkthrough of the 6th part of the second chapter. We've described the escape from Mommy Long Legs, and the way to ultimately defeat her.
Getting to Mommy Long Legs
After jumping up, you have to go through an underground tunnel. Inside, you will find many gold-illuminated bars. Keep going forward until you reach the ventilation tunnel.
When you go through it, you will reach another puzzle. First, turn the platform over so that it leads to the left. This way, you will get to the room from where you'll find the plushie you need.
The next step is to move the platform 180 degrees so that it leads to the right. Put the plushie at the designated point and then move on.
You will enter another hallway. You have to connect the objects with the beam of light again to open the next passage.
When you look up towards the light while walking through the tunnel, Mommy Long Legs will jump on you. Move back towards the door. After a short cutscene, the door will open and you will have to run away.
Escape from Mommy Long Legs
During the escape, you will run through various corridors and nooks and crannies. Use stairs and platforms to get away from the enemy.
When you reach the last tunnel, activate the red lever, which will open a passage through the tunnel.
You will find yourself in a room with 4 levers.Pull them in the following order:
Once you do it, look up and pull yourself up on the bar. Wait for Mommy Long Legs to pass under you twice, then resume your escape.
The next task you have to do is find and place 2 parts in the right place. One of them is in front of the furnace and must be placed in the mechanism above it.
You can enter the furnace by simply opening the door. Wait until the fire stops, though.
In the furnace, you'll find a part than needs to be places in the mechanism opposite it. Activating this object will open a passage.
Then, Mommy Long Legs will start chasing you again. Run straight ahead all the time, avoid her, until you reach the white corridor.
Defeating Mommy Long Legs
Run to the very end of the white corridor. At its end you have to put your blue hand on the mechanism. During this task, Mommy Long Legs will be in the area, but she will not attack you.
Pull the lever immediately after you enter the room. A cut-scene will play, showing Mommy Long Legs being killed.
The last part of the walkthrough for the second chapter of Poppy Playtime can be found on a separate page of the guide.