(b) Devki (Mahabharata): Kaikeyi was reborn in Mahabharata in Dwapar yug as Devki. Here because of her curse, incidentally she had to stay away from her son Krishna for 14 years (the period of Rama's exile), before he return to free her after slaying Kamsa.
(a) Kaushalya (Ramayana): Kaushalya was the eldest wife of King Dasharatha and the mother of Shri Rama. She was a very caring mother and equally loved all her step sons. She was heartbroken when her son was sent away from her for 14 years. But Lord Rama promised to be with her even in their next incarnation.
(b) Yashoda (Mahabharata): Kaushalya was reborn as Yashoda in Mahabharata. She became the fostering mother of Shri Krishna who lived His first 14 years of life with her. He kept His promise in this way.