Cats will kill their kittens if the situation calls for it, if they feel threatened, if the kittens are ill or if there is a predator outside and the kitten won't stop crying. If you can't get her inside, then prepare a place for her and the kittens outside. Use an old wooden crate, place a tarp over the crate, stuff the crate with hay and then cover the crate halfway to create a half door. Put food and water near the crate not in it to lure the mom inside. The collar looks like a flea collar? If it is, can you remove it? It isn't safe. Try and make her outside home as natural as possible keeping in mind that it has to be roomy enough for her to move around safely and the kittens have to be kept warm.www.kitten-rescue.com
will help you figure out what to do, should she abandon them. If you tell me what city you live in, perhaps one of my network rescue buddies can help you out. I can't promise, but I will promise to try and find you some help.