Two looks the most wrong, like Google Translate bad.
One appears to have a declension error and conjugation error, and literally means "This (feminine thing). We are defending." (bear in mind that the this here is not grammatically connected to the verb here"
The translation relies on what the "this" that the motto refers to. If it is this being land, country, i.e. America, than haec or rather hanc would be correct.
If the this is a general thing, than hoc would be proper.
I'd render the phrase thusly:
This, we'll defend
Hanc defendemus Literally "We will defend this (country, land)" with hanc representing terra, patria, America etc.