Answer:
Macbeth is realizing that all of his striving for power has been for nothing.
Explanation:
William Shakespeare's "Macbeth" revolves around the story of a general who commits horrendous crimes to get the throne of Scotland. The play or story deals with themes of greed, loyalty, evil against good, guilt, supernatural, and ambition, among others.
In the given quote from Macbeth from Act V scene v, we see Macbeth reacting to the news of his wife's death. He declares that "life's but a walking shadow, a poor player that struts and frets his hour upon the stage and then is heard no more." This is similar to the "The Seven Ages of Man" from Shakespeare's "As You Like It". Macbeth seems to realize the futility of all things, be it the ambitious desire to be in power or be mighty.
Thus, the correct answer is the second option.