What are your reasons for wanting to work as a petroleum engineer and/or not wanting to work as a mechanical engineer?
Regarding Options 1 and 2. I would suggest contacting a few petroleum engineering programs and ask them for their graduate placement rates since 1980 and recent starting salaries. Look at the placement rates during both the boom and bust periods. If your primary concern is financial, you can use that information to calculate and compare your expected return on investment for both options.
Regarding Option 3, you could be waiting a long time before a cyclical industry significantly increases hiring. When they do start hiring, chances are that experienced petroleum engineers and top petroleum engineering graduates will be hired first. Unless you have a spectacular resume, interview very well, and are willing to accept any petroleum engineering job / any where. I would expect your chances of success to be low.