If you have included your parents in it before donating it, they will be rewarded.

Saving you from the torment of the grave is in Allah’s hands and there is no specific reward for that.

Reciting suratul Mulk every night before going to bed saves you from
such torment.

i hv donated a small piece of land for madrassa where students will read and memorise quran, further i have contributed in construction also, will me and my perents both will be getting rewards, will it save me from azab e qabr and hell fire.