I think that "Hew" is "Hugh" but I can't say for certain unless I know the source for the spelling being different. Is it listed in a public file as "Hew" or in family records?
Joseph Scott was the coachman for Hugh Davis. I'm wondering if Martha was a relative of his. I have very little information on him and have yet to find any slave records/lists of Hugh Davis that may haver his name listed. Hugh Davis owned Homochitto Plantation but it may have been known as simply "Hugh Davis Plantation."
If I come across any info on a Martha Scott Blakely I will pass on to you. Good luck.
Mdavislaw