@Kiran_dass
There are three questions emerging in your post:
1.) What can the wife do if she is thrown out of house?
A1.) If she was thrown out of her matrimonial house without any reasonable cause then she can fiel a complaint for restitutio of her right to live in matrimonial home. First step should be to submit an application in "Crime Against Women Cell". They will not register a FIR but they would call both the parties for counselling and they would ensure safety for the wife. Still if the husband rejects to take her back, then take an order from the competent court.
2.) How to obtain her "Stridhan"?
A2.) "Stridhan" is the seperate property of the married lady. No one has any sort of right on this (not even her own parents) till she is alive. So you should include this point while approaching "CAW" Cell or the court.
3.) Steps against the in-laws?
A3.) If the wife was harrassed or beaten or similar atrocities were acted upon her, then you can mention these points also in your complaint to the CAW Cell or to the court. However, its upto you if you wish this marriage to stay or to take divorce. If you wish to stay, they refrain from filing a written complaint in this regard. But if you want divorce, then you should mention this point in your complaint as well.
MY PERSONAL SUGGESTION IS THAT "PLEASE" DON'T EXAGGERATE YOUR COMPLAINT. State only true facts in the complaint. Don't go by the words of any lawyer or relative to make the case strong. Whatever is the truth, you should follow and refrain from exaggeration.
//peace
/Saurabh.V