Help! My 3 month puppy won't sleep by herself!?

Recently my family and I got a sweet 3 month old coca poo. The only problem is she won't sleep by herself. We tried leaving her alone one night with a toy her and her brothers and sisters shared and a blanket with all my family's scent on it , but she ended up crying the whole night. The only time she doesn't cry and bark is when my mom sleeps next to her while she sleeps in her crate. My question is if she will ever grow out of this stage and is it all right that my mom has been sleeping next to her? Will this cause her to never sleep by herself? Thanks if anyone can help. God bless.