Expressing posession for someone whose name ends in "s"? Add -es, -'s, or just an apostrophe?

Answer 1

If it is a singular person, a simple apostrophe will do, but an 's would not be incorrect either:

Betty Jones Betty Jones' shoes Betty Jones's shoes

If it is plural (the Jones family) then you must first make it plural Joneses and then possessive with an apostrophe

the Joneses' car

Answer 2

People vary a lot on whether 's or just ' is correct. It's more a personal style thing. Often, one uses just the apostrophe when it is too difficult to pronounce with the extra s.