There was a debate on here awhile back (started by one of my threads ) as to whether or not a parent is eligible for a waiver through their USC child.... So the consul told them they were eligible for the waiver?
The waiver itself is a brief with documentation of evidentiary support showing the hardship to You (the USC) if your parents were not admitted. My husband is in Colombia, so I used statistics off of nationmaster.com to help show the dangers of the USC living in Colombia. If you have any medical conditions that would make traveling to Colombia difficult, use that and a letter from your doctor, etc. Financial concerns, etc. There's a lot of I-601 waiver examples in the stickys, but the majority are from spousal points of view and not child/parent.