My father has recently passed willing all property to my mother who's health rapidly deteriorating. They own two properties neither of which are directed to be willed. Are we better of having their vacation property willed, gifted, or sold before my mother passes?

Willing is better than gifting. It would probably be better to sell after death, since the tax basis will be better.

There are ways at time, depending on the size of the estate to do many things, you need to set down with a finicial planner or a estate attorney and see what is best for your situation.