I found Hugh Brown in 1940 census in Gloucester City. He was 82, widowed and living with his daughter Grace Mower.
If you can get to the New Jersey Archives in Trenton you should be able to find a death certificate for Elizabeth Brown between 1930 and 1940. If you look at death records after 1940 you may find Hugh’s death certificate.
Grace was married to Samuel Mower who was living with the family in 1930. You should be able to find a marriage certificate.