If Trump gets impeached, it would be because he is found to have broken the law, committing an offense serious enough for impeachment. It won't be because Hillary deserves to be president. Under the system that existed while the election took place, the people elected Donald Trump, fair and square. You can argue that Hillary got more votes all you want, but really, they were both playing to get more electoral votes under the system that existed, and for all you know, the counts would not have been the same had the rules been changed.
For example, there were less votes in Texas, usually thought to be a solid red state, than in Florida, a pure swing state. Texas has more voters, sure, but less people showed up because Texas was almost certainly staying red no matter what. In Florida, especially after 2000, people know that they basically decide the election in many cases. Had every individual's vote counted equally, I think more Texans would have voted.
So it's not like Trump didn't win the presidency over Hillary fairly.
But, if Trump commits some offense and is impeached, the chances that Congress will make Hillary Clinton president are virtually nonexistent. First of all, Congress has a Republican majority which will likely only be strengthened in 2018. Republicans don't want to see Hillary Clinton in office. Second of all, it says in the Constitution that the Vice President - currently Mike Pence - becomes president if the president is impeached. After that, there's a whole line of succession - after Pence is Paul Ryan (House speaker), then Orrin Hatch (President pro tempore of the Senate), then Rex Tillerson (Secretary of State), and on and on through Trump's cabinet.
So, in this scenario, Trump is impeached, and Congress does the "right thing" by throwing the Constitution out of the window, making Hillary president. However, they have no authority to do that without an amendment to the constitution. And they can't make an amendment to the constitution without the president - who becomes Mike Pence the second Trump is impeached.
To sum this question up, it is basically asking if Trump gets impeached, what are the odds that the Republican Congress will be able to convince Mike Pence to sign an amendment to the constitution so that Hillary Clinton replaces him as president, and get the necessary votes from fellow Republicans. I'd say none.