。
Shall we call it a night soon?
Literal
Soon, closing [to-に] shall-do-[tentative Kansai-しよか]?
お開き is an elegant euphemism for ending a party or gathering — literally 'opening' but used to avoid the unlucky word 閉じる 'close.' しよか is the Kansai-dialect contraction of しようか (volitional + question), and the lengthened ー adds a relaxed, friendly tone. A breezy suggestion to wind things down.