Deductions u/s 24 (b)

yes they can,

provided that necessay condition satisfied

NO they will not be able to claim deduction.

A co-owner, who is not a co-borrower, is not entitled to tax benefits. Similarly, a co-borrower, who is not a co-owner, cannot claim benefits.

Read more: https://www.indiantaxupdates.com/2012/11/06/tax-benefits-on-home-loan-in-india/

@ Anantamoorti B P

for claiming deduction U/S 24 assessee should be the owner of the house whether co owner or otherwise

So if they take joint loan , this will not gonna help them

Instead they can take house in their joint names then they both can get deduction under their respective heads of income