Any further question? What best to ask on one's last chance? What would one, certain wise but not free, ask/request if there is just one chance left?
You have the one final chance to ask one thing. What would it be?

That was Bahiya's problem in Udana 1.10 (quoted below). Bahiya, the advanced ascetic who was not enlightened, sought to understand in a short teaching the gist of the Dhamma that would free him.

This question would be like "What would be the shortest summary of the Buddha's teachings that is enough to liberate me from suffering?"


  Then Bāhiya, hurriedly leaving Jeta's Grove and entering Sāvatthī, saw
  the Blessed One going for alms in Sāvatthī — serene &amp; inspiring serene
  confidence, calming, his senses at peace, his mind at peace, having
  attained the utmost tranquility &amp; poise, tamed, guarded, his senses
  restrained, a Great One (nāga). Seeing him, he approached the Blessed
  One and, on reaching him, threw himself down, with his head at the
  Blessed One's feet, and said, "Teach me the Dhamma, O Blessed One!
  Teach me the Dhamma, O One-Well-Gone, that will be for my long-term
  welfare &amp; bliss."
  
  When this was said, the Blessed One said to him, "This is not the
  time, Bāhiya. We have entered the town for alms."
  
  A second time, Bāhiya said to the Blessed One, "But it is hard to know
  for sure what dangers there may be for the Blessed One's life, or what
  dangers there may be for mine. Teach me the Dhamma, O Blessed One!
  Teach me the Dhamma, O One-Well-Gone, that will be for my long-term
  welfare &amp; bliss."
  
  A second time, the Blessed One said to him, "This is not the time,
  Bāhiya. We have entered the town for alms."
  
  A third time, Bāhiya said to the Blessed One, "But it is hard to know
  for sure what dangers there may be for the Blessed One's life, or what
  dangers there may be for mine. Teach me the Dhamma, O Blessed One!
  Teach me the Dhamma, O One-Well-Gone, that will be for my long-term
  welfare &amp; bliss."
  
  "Then, Bāhiya, you should train yourself thus: In reference to the
  seen, there will be only the seen. In reference to the heard, only the
  heard. In reference to the sensed, only the sensed. In reference to
  the cognized, only the cognized. That is how you should train
  yourself. When for you there will be only the seen in reference to the
  seen, only the heard in reference to the heard, only the sensed in
  reference to the sensed, only the cognized in reference to the
  cognized, then, Bāhiya, there is no you in connection with that. When
  there is no you in connection with that, there is no you there. When
  there is no you there, you are neither here nor yonder nor between the
  two. This, just this, is the end of stress."
  
  Through hearing this brief explanation of the Dhamma from the Blessed
  One, the mind of Bāhiya of the Bark-cloth right then and there was
  released from effluents through lack of clinging/sustenance. Having
  exhorted Bāhiya of the Bark-cloth with this brief explanation of the
  Dhamma, the Blessed One left.
  
  Now, not long after the Blessed One's departure, Bāhiya was attacked &amp;
  killed by a cow with a young calf. Then the Blessed One, having gone
  for alms in Sāvatthī, after the meal, returning from his alms round
  with a large number of monks, saw that Bāhiya had died. On seeing him,
  he said to the monks, "Take Bāhiya's body, monks, and, placing it on a
  litter and carrying it away, cremate it and build him a memorial. Your
  companion in the holy life has died."
  
  Responding, "As you say, lord," to the Blessed One, the monks —
  placing Bāhiya's body on a litter, carrying it away, cremating it, and
  building him a memorial — went to the Blessed One. On arrival, having
  bowed down to him, sat to one side. As they were sitting there, they
  said to him, "Bāhiya's body has been cremated, lord, and his memorial
  has been built. What is his destination? What is his future state?"
  
  "Monks, Bāhiya of the Bark-cloth was wise. He practiced the Dhamma in
  accordance with the Dhamma and did not pester me with issues related
  to the Dhamma. Bāhiya of the Bark-cloth, monks, is totally unbound."