In which county can I file for a restraining order?
You can file a petition in the family court or in the district court (depending on your relationship to the abuser) in the county where you live. If you have moved to another county to avoid further abuse, you can file in that county no matter how long you have been living there.* However, if you are trying to keep your new address confidential, filing in the county where you have fled to would likely not be a good idea since it would alert the abuser to the fact that you are living in that county.
* RI Gen. Laws §§ 8-8.1-2(a); 15-15-2(a),(d)