Thanks for the question.

For all three of these plants, expect some leaf yellowing and even leaf drop over the winter. This is due to these plants going into a period of dormancy and reduced light. This means that for each plant you will need to decide between having it go into a state of complete dormancy (reduced light and temperature and relatively little watering or fertilizing) or trying to maintain it as a house plant (maximum light with occasional watering and fertilizing). At least for geraniums, I have had most success in growing them as house plants during winter months. The following should assist you:

https://www.chicagobotanic.org/plantinfo/faq/overwintering_hibiscus

https://www.costafarms.com/blog/winter-hibiscus-care-tips

https://www.gardeningknowhow.com/ornamental/vines/mandevilla/winterizing-mandevillas.htm

https://gardenandbloom.com/blog/how-to-overwinter-a-mandevilla-plant

https://hortnews.extension.iastate.edu/2004/9-17-2004/geraniums.html

https://empressofdirt.net/overwintering-geraniums/

Good luck!!