Is Sudden Withdrawal From Premarin Safe?

My friend who is 78 years old, has been taking Premarin for over 30 years. She has been told that she should not be taking it, but instead should use bio-identical hormones. Does it make any sense for her to switch now? She has had lupus for over 30 years, and now has a problem with increasing weakness in her legs called myopathy. With all this going on, should she even be worried about Premarin (which she needs for hot flashes)?