My wife is currently in the US on an f-1 visa. Here course of study is over on July 7. Is there a way for her to stay in US until Feb 2019? Legally

Your wife could perhaps take on another course of study in another subject. She could also register for continuing education courses such as offered by an institution such as Kaplan. Another short-term option is applying for a change of status to B-2 visitor, but such could only be requested for 6 months, and she would have to make a further application to extend all the way to February. As you are a U. S. citizen, have you thought about the possibility of sponsoring her directly for permanent residence? If so, you and she could file a concurrent I-130 Petition for Alien Relative and I-485 Application to Register Permanent Residence or Adjust Status with U.S.C.I.S. at any time, and she would be allowed to stay in the U. S. during the pendency of the application. If she needs to travel, she would apply for an I-131 Application for Travel Document and for work privileges form I-765 Application for Employment Authorization. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.

If your wife entered the country legally, then you can file for her adjustment of status to obtain her green card, despite that she will overstay her f visa. My advice is always that the foreign national should never leave the country until she has her green card. You can retain the services of counsel anywhere in the US for legal representation. Most of us give free consulations over the phone.