Congrats to your friend! Pits are great dogs and very smart.
1. She is not fully housetrained. So go back to housetraining 101 as if she were a puppy. Take her out every hour, reward heavily (treats, petting, praise, running around, etc.) every time she pees/poops outside. Do not let her roam the house unsupervised. So she should either be on a leash and attached to her owner's belt loop or in a crate if the owner needs to leave. The crate should be big enough for her to stand up in, turn around, and lay down. Dogs are less likely to pee/poop in their sleeping space and they will hold it.
2. Does she have a UTI? Sometimes dogs can get UTI's and it affects their ability to hold in their urine. A vet trip to rule out this possibility may be in order.
3. You say she pees on the clothes/sheets. Dogs will do this because those articles smell like their owner. It isn't out of spite or anything. She may do this if she is stressed being left alone. When the owner has to leave the house give the dog a Kong toy that is filled with food. I like to put some kibble, green beans, and dog treats in mine. Then you use peanut butter or PLAIN yogurt to kind of smush it around the top. Freeze it. With the dog in the crate, give her the Kong, and now she is contained and has something to do.
4. Walk the dog and make sure she pees before the owner leaves the house. This will let her burn off a little energy, empty her bladder, and be satisfied enough to just want to nap while the owner is gone
5. Do not punish the dog if she pees on something. She won't understand why she is being punished which can lead to more fear and more peeing. Clean up all pee with an enzymatic cleaner. Nature's Miracle is a popular brand. Wash all the soiled laundry with this. It takes out the "pee here!" smell that is in dog's urine.
Those are my tips. Hopefully your friend has some progress.