A handwritten will needs to be signed by the testator and attested by at least two witnesses to be legally valid. Your grandfather's will, lacking witness signatures, is therefore invalid in the eyes of the law. In this situation, your grandfather's property will be distributed among his legal heirs, which include your grandmother, your aunt, and yourself. To transfer the property, you may need to obtain a No Objection Certificate (NOC) or a registered relinquishment/gift deed from your aunt and grandmother.