Is it permissible to marry a girl whom the mother rejected because she is not from the Gulf, and is this considered disobedience to parents?

The questioner should appease his mother so she accepts his marriage to the girl, as that is more conducive to stability. If she insists on refusing, then he must be dutiful to his mother and seek another wife whom his mother approves of; because Allah has enjoined kindness to parents, as stated in His Almighty saying: "And We have enjoined upon man [care] for his parents. His mother carried him through hardship upon hardship," and in the Hadith: "Indeed, Allah enjoins you concerning your fathers, indeed, Allah enjoins you concerning your mothers, indeed, Allah enjoins you concerning your mothers."