I feel afraid to pray tahajud as I am the only one who is awake and everyone is sleeping.
I heard unmarried girls should not pray tahajud everyday as jin may fall for you and can cause problems with marriage.
Will 3 Surah qul 3 times each and ayat Al qursi 3 times be sufficient to be protected from anything

What you heard has no meaning.
Yes, reciting Ayat Al-Kursi, and the Qul surats is sufficient -Allah willing-for protection