Placement of period after abbreviation inside quotation marks

2018-06-05 11:45:55

The most common one is "vs.."

The most common one is "vs.".

The most common one is "vs."

Which of the above features the correct usage of a period after an abbreviation inside quotation marks?

And, also, which of the below is correct?

Richard, Rich, Rick, etc..

Richard, Rich, Rick, etc.