The essentials for a home office are:
Furniture (ergonomic desk and chair are topmost on the list)
Reliable (dedicated, if possible) internet
Computer (ideally a desktop, but keep a laptop as a backup)
Collaboration Software (communication and project and task management are a must-have)
Writing aids (notepads, notebooks, as well as pens and pencils)
Other planning materials (calendars, planners, peg boards, or cork boards)