Hi welcome to Health care magic forum. After one year of the cesarian section she has developed an opening of stitches means , it must be an abscess
probably due to nonabsorbable catgut remained there by mistake.
I hope there wont be any problem , after cleaning the wound and removal of the unabsorbed suture and use of antibiotics will clear the problem.
Besides i advise you to follow some diet recommendations as avoid taking potato, pulses, and fish to minimise the pus formation and promote the healing.
Wishing for a quick recovery and thanks for calling.