What to do about this baby

I babysit this baby, she’s 7 months old and I have a baby who is 6 months old so they love play together. The baby’s mom dosnt have very good hygiene. Once the bathroom down stairs bathroom didn’t have toilet paper because I hadn’t put it in there yet and she uses the bathroom so I give her a pack of wipes to take and she said”it’s ok I’m going home right after this anyways”. Every single day when she drops her baby off her baby smells like nasty milk and just funky. She always has adult hair and tried who knows what under her neck. When I change her she has a strong odor down there. Her clothes smell like they have been laying in the dirty clothes basket for weeks. As soon as she comes to be I immediately give her a bath and put her clothes in the washer and put my daughters clothes on her. I feel bad! I don’t know how to bring it up to her because I don’t want her to be offended and find someone else to watch her baby because who knows who she will let watch her. How could I nicely say that her baby is gross?