There's a couple of things you can do.If you have $500 dollars, pay a really large dude to rape her. Make sure the really large dude punches her in the head while he rapes her and he has to tell her "Make some noise, b****, make some noise." You may want to consider selecting and paying this anonymously through a proxy, to avoid anything coming back to you.
I don't really like that option, but it is an option.
The second option is much much better, but it requires that they have a natural gas source somewhere.
If you can, procure a tank of carbon monooxide. After everyone goes to bed, pump it into the ventilation system of the house. You have to be very careful to pump it correctly. You may want to consider bringing scuba gear. 😐 Anywho, after they are all dead, turn their gas stove on and leave it on.
If they have a carbon monoxide detector, you're ****ed. If they have motion sensors, you're ****ed. If they have infrared sensors, you're ****ed. However, I am doubting that she has any of those because she has shits over at her house at all times of the night. If she armed the system before hitting the sack, one of her shits would set the alarms off.
You'd want to poor in the CO into the source of the AC system, that way the CO spreads to the rest of the home, killing all occupants.
Be very sure to wear gloves and a hair covering. Long sleeves as well. If you can mange. Wear a pair of shoes that you have never worn before. Have someone who is not a family member and not a close friend purchase them. If you want to really help out in the shoe department, you could scope out some frequenters to her place and see what shoes they wear. Burn them when you get done...preferably not in you place. Try not to scratch ANYTHING while in their house. It could be all over if you leave an eyebrow hair...slim..but still a possibility. To keep from sweating, wear a long sleeve under armor shirt.
Also, you'll probably have to wait for the AC unit to turn on before you start pouring in the CO. There's one thing that I am concerned about...the CO canister may have to be carted on wheel. If that is the case, it may leave tracks.
Make sure you carry the cannister over the grass if you have to cross the grass. Obtain the CO cannister (large), via anonymous proxy as well.
There's a few other things I'd like to add to this, but this is the general idea on how to take care of it.