此句错误。because of 和 in light of 意思重复。去掉其中一个即可。

I certainly hope it 's not because of Dr. Lim's recent promotion to Chief of Surgery that she's now your supervisor.
I certainly hope it 's not in light of Dr. Lim's recent promotion to Chief of Surgery that she's now your supervisor.

hope 的宾语从句是个强调结构。还原后的句子是：

I certainly hope she's now your supervisor not because of Dr. Lim's recent promotion to Chief of Surgery.