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 is His slave and Messenger.
Since you have performed the obligatory Hajj, then giving the expenses of Hajj in charity to those in need of food, drink, shelter and medicine is worthier, better and greater in reward in the sight of Allah than voluntary Hajj or performing Hajj on behalf of grandfathers, grandmothers and even fathers and mothers. That is because if they cannot afford Hajj, they have got an excuse, and Hajj on their behalf becomes recommended in this case. If they can afford it, then the expenses of Hajj and ‘Umrah are to be taken from their properties (or estates if they are deceased).
In general, if you can perform both matters, this is good so that you give charity to the needy and perform Hajj on behalf of your grandfathers and grandmothers.
May Allah reward you for your concern with the conditions of the Ummah of Islam. We ask Allah to amend the conditions of the Muslims.
Allah Knows best.