You may file an I-130 and then leave the US. You are not required to remain in the US. Please note, if your I-130 Petition is approved, then your mother will be eligible to apply for permanent resident status. You as the petitioner must be "domiciled" in the US in order for your mother to be able to apply for permanent resident status. Please let me know if you have other questions.
Answered on Aug 19th, 2013 at 3:08 PM