You need to get down to the specifics of a particular van year/make/model. Few, if any, vans are towable as-is, but most could be with some modifications. Front wheel drive vans generally need to use either a tow dolly or have an expensive transmission lube pump added. Rear wheel drive vans typically need a drive shaft disconnect, also pricey.
Could she use a large SUV instead, e.g. a GMC Acadia or Ford Explorer or Jeep Cherokee? Or a Taho or Suburban? They are 4-down towable in most configurations and years.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL