Where to Seat Son and Brother

I am having my oldest son and my brother give me away at my wedding because my father has past away and I was wondering should they sit at the head table or just at my family's table with my mother?

The person/people who give you away do not need to sit at the bridal/head table (which typically is just the bridal party - bride/groom bridesmaids and groomsmen).

It's perfectly acceptable to have them sit with your mother at the family table and they/she may prefer that. You can, however, have anyone you want sit at the bridal table. The size and layout of the tables and reception room may also determine how many people comfortably sit at each table.