Hello
I'm not sure about it being Sinne - or the last letter being an 'e' especially if compared to letter formations in the Cause of death of "Uremic Coma"
For the mother, I think her surname is "Pon" on both this DC and on the 1880 Census:
In 1880, Hebron, Orangeburg, SC
Head: James Pon 60, Farmer, b SC (parents b SC)
Wife: Satyra Pon 70, Attends to housekeeping, b SC (parents b Not Known)
Gr-Daughter: Francis Carson 13, b SC (parents b SC)
And next door, is :
Head: Luis Pon 22, Farmer
Wife: Sylla Pon 20, works in Plantation
Dau: Irena Pon 4
Dau: Henrietta C Pon, 2 mths
All born SC, as are parents.
Also some of the records I came across, corrections offered "Boone" as a surname, instead of Pou or Pon - perhaps changed down the line?
Cheers
AMBLY