Translation:I saw you, Mara.
"Mara" is neither subject nor object.
(The subject is "I" and the object is "you" -- both are shown by the prefix qa-.)
mara is a vocative -- just an expression used to call the listener's attention to the fact that you're talking to him or her. For clarity, it should be set off by a comma, as the English sentence does.
I'll delete this sentence and replace it with a version that does so.
Apologies for the confusion.