Need some advice

My best friend's kitten was killed this morning by his roommates dog. I'm thinking dog thought the kitten was a toy and accidentally killed him. The dog is very friendly and playful but the kitten was very small and the dog owner thought it would be a great idea to get another cat today for my best friend and I would take the cat in if I could so it would have a safe place for it so my friend can get a door for his room as they only have baby gates to keep two medium sized dogs in different rooms but I have a cat of my own who has anxiety around people and other cats. I just dont know what to do I'm just scared about the cat they got tonight will get killed to. I don't think that dog is an aggressive dog she probably hasn't been around any cats or shown how to behave around them. I don't think she should be put down and I doubt the dog owner will train her to leave the cat alone but even if she does train her what will she do when no one's home to watch her