Is it true that four men will enter Hellfire with a woman if it is decreed for her?

There is no authentic or weak hadith with this meaning. A Muslim does not enter Hellfire for the sins of others. Allah the Almighty says: (And every soul earns not [anything] except for itself, and no bearer of burdens will bear the burden of another) (Al-An'am/164). This principle was clarified by Allah in previous scriptures, as in Surat An-Najm (53:36-39). The Messenger of Allah, peace and blessings be upon him, delivered a sermon during the Farewell Pilgrimage, stating: (Indeed, no one who commits a crime is accountable except for himself. Indeed, no one who commits a crime is accountable for his child, nor is a child accountable for his parent.) Thus, no one is held accountable for the crime of another.