1. 마음을 편히 하세요 / 해 주세요. 2. 마음을 편히 먹으세요 / 먹어 주세요. 3. 마음을 편히 가지세요 / 가져 주세요. Yes, all can be translated as "Take it easy" or "Relax". The -아/어 주세요 versions are less common, and imply that the speaker caused or provided the occasion (since -아/어 주다 usually means doing something for someone else). 마음을 편히 가지세요 sounds like the most general and proper advice. 마음을 편히 먹으세요 sounds colloquial, more appropriate for conversation, especially when the person is facing a difficult situation. 편히 하세요 is more often used for physical posture, as in 자세를 편히 하세요, a phrase a doctor/nurse might say to a patient. There is also a related adverbial phrase, 마음 편히/편하게, which is very common. E.g. 마음 편히 쉬세요 (Take a rest forgetting all worries), 마음 편하게 즐기세요 (Relex and just enjoy it), 마음 편히 다녀 오세요 (Have a worry-free trip).