ANSWER:
She is not obliged at all to serve her in laws. Her duty is towards her husband and children.
She has all the right in islam to ask her husband for a separate accommodation. Your in laws have no say or right in this. He must fear Allah and give you your rights.
However, you must be smart in dealing with this sensitive issue. Do not nag your husband about this, rather be patient and talk to him in a diplomatic and loving manner when he’s in a good mood.
You must be diplomatic and smart about how to approach him when he is in a good mood and not nag him about this. You have to weigh all options and choices you have and select the right one on the long run and not on the short run.