A 55 year old female presented with tingling sensation in her hands and feet & pain in her legs during night time. She had type 2 diabetes for 15 years. O/E- loss of ankle deep tendon reflex, loss of position sense of great toe, decreased pinprick sensation over ankles & wrists. Her recent HbA1c was 8.9%. She is currently managed with insulin and metformin. She is diagnosed with diabetic polyneuropathy. Which of the following medications can be used to treat pain associated with diabetic neuropathy?