I am currently prescribed to take 150mg of ranitidine twice daily, is it safe to take 2 200mg of ibuprofen together?

That depends. If you are taking the ranitidine 2x/day for some moderately/severe acid condition, then taking 400mg of the NSAID Ibuprofen may irritate you even further. Your treating physician who knows your case best would be able to tell you what meds are best for you, if you can not reach her/him, tylenol (acetaminophen) would be better option until told otherwise.
Ranitidine. Ranitidine or zantac (ranitidine) is a relatively safe medication. The use of Ibuprofen or Motrin is usually not contraindicated.