بسم الله الرحمن الرحيم
(1) It is not good to take loan without a severe need. It remains like a burden in mind every time. Thus you should avoid taking loan without a severe need.
(2) It seems that you are under heavy debt or you cannot accompany your parents-in-laws for hajj independently. If it is so, then why do you put yourself in trouble for a Nafl act. Keep on praying Allah and when Allah provides capacity and ease in future then make intention to perform it.
(3) Amen! Read the following dua after each salah for repayment of debt:
اللَّهُمَّ اكْفِنِي بِحَلَالِكَ عَنْ حَرَامِكَ وَأَغْنِنِي بِفَضْلِكَ عَمَّنْ سِوَاكَ.
Allah knows Best!
Darul Uloom Deoband