My grandma has an adopted 25 yrs old woman.. my grandma have been looking after her since she was a little girl.. and since then she has been creating many family problems.. I have been staying in Srilanka and I got bak here very recently.. and I go and stay in my grandma's house in every other day... and the adopted woman also lives there.. now she has a 12 yr old son... and she is saying that I don't deserve a place in that house.. and she is jelous because I mite take her son's place.. what can I do? Why don't I deserve to be in my grandma's house? Help me.. give me some ideas.. of what I should do?

You deserve to be in your grandma's house as much as they do.
Don't worry about what she says or thinks unless she starts trying to convince your grandma to not let you be there. Don't do anything to make it seem like you are a threat/competition to her son.
My smart mouth I would say, "and why do you DESERVE to be here?"

Don't worry about it. If anything YOU deserve to be there more than she does plus your really related to her and she's not even real blood to you guys. If she really is bothering you just tell your grandma.

Good luck!