If used at all with the parentheses, it should follow the closing parenthesis.

When a complete sentence is enclosed in parentheses, the period falls within the parentheses.

When the enclosure is a brief passage at the end of a sentence, the period falls outside the parentheses.
Do not put a period before the apostrophe and the possessive _s_ as in _Co.'s_.

The word _Company_ may be abbreviated to _Co._ although it is not desirable to do so if it can be avoided.

The possessive of _Co._ is _Co's_.
SUMMARY 1.