What is the meaning of [The be all and end all]

The whole thing. The last word. Something that so entirely suitable as to eliminate the need for a search for an alternative.

‘The be all and end all’ was coined by William Shakespeare in Macbeth, 1605. The bard gives these lines to Macbeth, when he is contemplating assassinating King Duncan of Scotland and taking the throne for himself.:

If it were done, when ’tis done, then ’twere well
It were done quickly. If th’ assassination
Could trammel up the consequence, and catch
With his surcease, success: that but this blow
Might be the be-all and the end-all