Huge Huge stray dog problem. HELP.?

Hi. an hour ago i opened the door of my house and i found a young scared puppy outside my door. She's about a month old and is really scared. I live in an apartment building and at the moment the rest of the houses are empty. I've given her milk and water and i've closed the main door of my building so that the other stray's don't end up killing her. She already looks slightly hurt. I tried to explain the situation to my mom but it was of no use. She just freaked out. What do i do?