السلام عليكم و رحمة الله و بركاتهI heard that old women do not need to wear hijab?So can young men mix with them??

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu ʻalayhi wa sallam, is His Slave and Messenger.

The verse refers to the aged women (of post-menstrual age) who attained the age at which men do not have any sexual desire for them nor do those women have a desire for men.

Al-Qurtubi said, "Rabeeʻah said that the word Qaaʻid used in the verse refers to the very old woman who is regarded as absolutely unattractive and men do not have any sexual desire for them.'"

It is prescribed for such old women to put off the outer garment such as the ʻAbaayah and Jilbaab (long, flowing, baggy over garments worn by Muslim women) without displaying adornment or revealing the ʻAwrah.

It does not mean that they are given a legal concession to reveal their ʻAwrah. Al-Aloosi wrote, “It means that such old women are allowed to put aside their outer garments such as gawn, ʻAbaayah, or Jilbaab worn over the Khimar and it should not lead to revealing their ʻAwrah …”

Some scholars held that it is permissible to sit down with such old women and look at them (with their faces) unveiled. Some even held that it is allowable to shake hands with such old women. Al-Mawsooʻah Al-Fiqhiyyah Al-Kuwaytiyyah (Kuwaiti Encyclopedia of Islamic Jurisprudence) reads, “It is allowable to look at and touch the very young girls and the old women who are not sexually desired by men given the absence of the Fitnah (temptations). It is impermissible as long as there is fear of potential temptations …”

It is better for the Muslim man, who attained puberty, to evade intermixing with such old women. The ruling on such an act is rather less stringent as far as the young men who have not reached puberty are concerned.

Allah knows best.