Is the questioner sinful for not giving money to the sisters of her deceased aunt, and will her sin be forgiven by her imprisonment and suffering?

Your aunt bequeathed all her estate to you, which is not permissible in Sharia, as a will is only executable up to one-third of the estate. The remainder is to be distributed among the heirs according to Islamic inheritance law, whereby your mother and her maternal aunt receive two-thirds equally, and the rest goes to the asabah (agnatic heirs) if they exist; otherwise, it is returned to them (the mother and maternal aunt).

Therefore, if the amount you took is equal to one-third of the estate or less, then it is rightfully yours. However, if it exceeds one-third, you must return the excess to the heirs. This amount will remain a debt upon you until you repay it, as your imprisonment does not exempt you from returning the money to its rightful owners. You must hasten to restore these rights, as Allah Almighty says: (Indeed, Allah commands you to render trusts to whom they are due) An-Nisa/58, and the Prophet, peace and blessings be upon him, said: (The hand is responsible for what it took until it returns it). If your mother pardons her share, then that is permissible.