how to make a girl as a friend ?

I think that you are not offering just friendship to that girl. It is something more than that. If you are a school boy, just stay away from such things and concentrate on your studies. If you really like her and see her just as a friend, then just go to her and tell her that you want to become her friend. If she feels good, then fine or else, you are not looser because before this also she was not your friend and her refusal to become your friend should not cause much problem to you. It is important that in friendship both the persons are in agreement and then only the friendship can flurish.

well, why could you not talk to her when her mother is there? Is the mother evil or something? Heck getting in good with the mother is not a bad idea either you know. Just go talk to her. Find SOMEthing that the two of you have in common and talk to her about it. Ask her if she has seen your dog (if you have a dog) or if she likes dogs or whatever. Just be nice and be friendly, but don't be creepy.