Hi Vinay,
If the property is let-out, compute the income from such house property as if the property is owned by one owner and thereafter, the income so computed shall be apportioned amongst each co-owner as per their specific share u/s 26. This means the interest u/s 24(b) can be divided and apportioned between co-owners.
Here, you are talking about CO-APPLICANTS but not co-owners. If loan is taken by co-applicants and the property is in the name of one of the applicants, then the interest u/s 24(b) can be claimed only by such co-applicant who is a registered OWNER of the house property.