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I am sorry to hear about this situation. You have been what is known as a tenant at sufferance, meaning you have lived there at the discretion of the owner (grandfather) without having to pay rent.
Now that someone else owns it, they can ask you to leave. However, under Civil Code Section 1946 et seq, the new owner must give you SIXTY DAYS NOTICE in writing to relocate. If you do not within that time, then, they can evict you.
The fact that the utilities are in your name does not change the above, I am afraid.
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