If it is registered in her name-she should be able to transfer the title.
If she has lost the title-she should be able to apply for a lost title so she can
transfer to you.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.
Your mother in law can apply for a duplicate title and once she receives it, she can transfer it to you.
Please note that I am answering this question as a service through Avvo but not as your attorney and no attorney-client relationship is established by this posting. An attorney-client relationship can only be established through signing a Fee Agreement and paying the necessary advanced fees.