there are a couple of things more than what Dr Habib has said.
Is this boil painful? - if yes then what is most important is the post surgical hygiene. I would advise your friend to do the following things
1. give hot compressess to the eyelids once or twice in the days.
2. this should be followed by gentle massage
of the eyelids to remove any scretions
3. the eyelids have to be washed with a very mild shampoo like a baby shampoo. this removes most of the dirt accumulating there and helps prevent boil formation.
If the boil if of the non painful variety and is coming back again and again at the same place then it can be something serious. there is a entity called sebaceous cell carcinoma or a type of cancer that can present in this way. Its better to do a histopathology study of the exceised material to rule of SCC. this generally presents in the advanced age though.
Hope this helps. Do get back to us with the progress on your friend.