Please give my best regards to him.

请代我向他请安问好。

Best regards to you and yours!

向你和你的家人问好！

My best regards to you and Ruth.

谨向您和鲁思问候。

Please give my best regards/wishes to…

请给……我最真诚的祝福。

For now our best regards.

最好的祝福。