A family friend, who had been sharing the beach-front bach with the family at Mangakuri Beach, said the mother was recovering well.
"Her husband just rang this morning to say she's ok, and the boy's ok," Osha Bianco said.
The ordeal had cut their holiday short.
"We were all [supposed to be] here until tomorrow, but we're all feeling very flat this morning, and very heavy-hearted," Ms Bianco said.
"It could very well have been us too, because we were in the water next to them as they went."
Ms Bianco's son had been playing with the other boy when he got caught in the rip.
"Anything we could do - I just legged it up the beach to ring 111, and my elder son went to get the father who was going for a walk on the beach."
Ms Bianco said she was "quite hysterical" watching her friend struggling in the waves while she stayed on the phone with emergency services.
"I could see, helpless, from the bach that we're staying in, the two of them in there, and then they would disappear, and then we could see them again."
Her friend was "limp" and exhausted by the time she made it back to shore, she said.
"It all happened very quickly."
Local man Ian Waterson helped rescue the mother by jumping into his 4WD farmbike and driving straight into the ocean.
The 75-year-old man said: "When I spotted them the boy was further out than the lady and she was obviously trying to get to him ... the two of them got caught in a rip and ended up out beyond the surf. They were probably 150m to 200m off the beach."
Mr Waterson said he was about to call 111 but realised help wouldn't arrive fast enough so "took off down onto the beach" on his 4WD.
As he was heading into the water, he met the woman's husband, and he jumped on board.
"I went out on the water in the 4WD, it was floating along ... It was probably a metre or so deep when we got to her," he said.
"By the time I got to her she was very exhausted. I said to him, 'just grab her under her arms and we'll get her up onto the beach'."
The woman had taken in a lot of water, he said.
The woman and her son were flown to Hawke's Bay Regional Hospital for treatment. A spokeswoman for the hospital said the boy was discharged last night, while his mother was discharged this morning.
The family declined to comment when contacted by NZME. News Service this morning.
-- additional reporting: The New Zealand Herald
