This would be better in the Towcar section to be honest, but what model/spec of Pug does she have? I think it'll struggle a bit to be honest, but need more info etc., in case her car has limited tow weight limit.
Any idea what the laden weight is of the van?
Depends on the kerbweight of the car and maximum laden weight of the van she is considering. Ideally you need the maximum weight of the van not to exceed 85% of the kerbweight.
You may find the 1.4 engine just doesn't have enough torque/power to pull sucessfully even if the weights seem OK.
You have not given enough information really - model body type,age and fuel would be good. Lets assume its a 206 5 door petrol hatch. 1998 - 2009. Weight of the car = 1025 kg and braked towing limit = 1100kg so yes it will tow a 622 kg caravan.