Yes, they can go for Hajj. Their Hajj will be correct. It is possible that through the duas of Hajj maybe Allah will help in paying off the debts. However, permission should be taken from the creditors before travelling.
Grave of Zaid Ibn Haaritha R.A | Jordan | 13.8.25
TafseerRaheemi · Grave of Zaid Ibn Haaritha R.A | Jordan | 13.8.25