What are my options?

Check at the courthouse deeds office to see if his home is in his name alone.  If it was not made payable on death with others or joint with rights of survivorship with others, thus your father owned it in his name alone, hire the best probate lawyer you can find and open a probate.  You will now have the law behind you and you will be able to recover the house and other things and throw the sister out, unless there is a will that leaves all this to her and disinherits you.  How much of the estate you will get to inherit will depend (if there is no will) on whether your father was married or had other children.  If you are an only child and your father was not married, it all belongs to you and you can be named administrator of the estate.  But there are many other facts to gather to give you certainty of your position.  Hire an attorney ASAP.