Purport

This is the last Shloka of this chapter. In the last four shlokas, Bhagwan Shri Krishna explained the four different ways to achieve the supreme state of Bramhan and liberation. In this Shloka Bhagwan reveals the ultimate and final truth, that he is the final purpose of all prayers, worships, Yajna and Tapasya. He is the Supreme Lord of all worlds and living beings. He is the real friend of all living beings. All methods of worship, Yajna and Tapasya and service ultimately reach to Bhagwan Shri Krishna.
This fact is described elsewhere in Shrimad Bhagvad Gita:
"All, who in whatever way worship me, I reward them accordingly as all men ultimately follow my path in all respects, O son of parth(Arjuna)."
--Shrimad Bhagvad Gita (Ch4: Sh11)

A human may select any path and will get the same result of Moksha. One who thus knows this truth never gets bewildered by material variations. He selects any path as prescribed earlier and he is sure his devotion will reach to Bhagwan Krishna. The supreme Parmamta of all world and the most merciful Shri Krishna will take care of him. Such devotee hence achieves ultimate peace.