Cricket Puzzle: If a team requires 1 run to win from 1 ball with 1 wicket remaining, and the wicket-keeper stumps the batsman out on a wide ball, what is the final result of the match?

The batting team wins(by 1 wicket). The wide happened first and then the stumping. So, with the wide itself, the batting team wins, and all other actions after it (the result of the match is decided) remain void. 

Popular incident:

One most popular and similar incident is from IND vs SL in 2010

When Sehwag was batting on 99* and IND needed 1 run to win.

To avoid Sehwag from scoring a century, Suraj Randiv bowled a deliberate no-ball and thus, IND won by the run given by No Ball.

Later on, Dilshan and Randiv were found guilty and were punished.