my coworker is supposed to finish her job contract on March 31st. however, she keeps coming back to the office almost every day. i wonder why the staff in the general office has not approached her to collect the keys and ID etc. i have asked her why she's still around. she just replied, "yes i am." it seems like she'll tag around like forever. since she's no longer working here, she should not be using our resources, like air conditioning, free internet, free water, etc. but i'm not blunt enough to bug her. what should i do? any suggestions?