Mahram relatives of a woman are as follows:
Father, grandfather, maternal grandfather, (up to above), son, grandson, (to below) brother, nephew (bhatija and bhanja), foster-brother, father-in-law etc.
And the mahram of a man are as follows:
Mother, grandmother, maternal grandmother, (up to above) daughter, granddaughter, niece (to below), sister, khala, phuphi, foster sister, mother-in-law etc.
Allah knows Best!
Darul Uloom Deoband