All of them (home, away at school). Not much with the technical support, she just need a durable, all purpose laptop which will last for 5 years.
Then I would strongly suggest either the Dell or Lenovo with an extended warranty. Be sure to go with a business class machine that is designed to take the use and abuse of travel as well. Don't go with a consumer class system as they generally aren't designed with that sort of longevity in mind. When purchasing your warranty, make sure you select an option where the vendor will come to you and fix in your location, regardless of where you are (useful if your sister is away at school).