The company has broken its silence since the incident with a report detailing what happened to her and another climber in the group, who also died.
The company said other people posted news about Dr Strydom's death before they had a chance to contact the family, while the team had been busy recovering her husband Dr Gropel.
"At the moment we are assembling a rescue team to try to retrieve the bodies," the company said in a statement.
Dr Strydom's mother Maritha commented on the Facebook statement with: "We never had ... any contact from anyone from your company, now, almost 48 hours after my daughter's death. I want her body back."
The lecturer's sister Aletta Newman confirmed to AAP that they still had not heard from the companies.
South African born Dr Strydom's devastated older sister said she only learned of Marisa's death by Googling for news of Everest before going to bed on Saturday night.
Mrs Newman said on the family still hadn't heard from expedition organisers Seven Summit Treks, despite AAP passing on the family's contact details when the company claimed not to have them.
"I found this article from the Himalayan Times naming her as having deceased. I was shaking like a leaf because no-one had told us anything, that's how we found out. We just couldn't believe it. We are just in absolute disbelief and shock," Mrs Newman told News Corp Australia.
Getting her sister's body down was "absolutely what we want", she told AAP.
Dr Strydom, a lecturer at Monash University's Banking and Finance Department, had previously climbed Denali in Alaska, Aconcagua in Argentina, and Kilimanjaro in Africa.
She and Dr Gropel aimed to be the first vegans to reach the summit of Everest.
Mrs Newman the family had full confidence in her abilities.
"It was just so unexpected. We are so absolutely devastated."
The family has been told an attempt may be made to bring Dr Strydom's body down the mountain, but nothing was certain.
"Because the body is so high up there is a chance they might not be able to get it, and that's really hard for us. We don't want her to be there."
Maria Strydom and husband Rob in Nepal last month. Photo / Facebook
Dr Gropel's parents, Heinz and Patricia, flew out of Australia around midnight to reach Nepal where they hope to help their son retrieve his wife's body.
They also hope to fly their son to Kathmandu by helicopter.
"He is able to speak but obviously he's absolutely distraught - he's absolutely broken," Mrs Newman said.
"He's very determined not to leave Nepal without his wife."
Operational manager Furtengi Sherpa told News Corp Australia that on Friday Dr Strydom had almost made it to the top.
But she suffered from a "lack of energy and weakness" he said and had to turn around and start back while the rest of the party reached the top.
Furtengi Sherpa said Dr Strydom and her personal sherpa got back down to Camp 4 that night and had started to head back down the mountain again on Saturday.
But her tiredness and lack of energy continued despite being given oxygen.
Finally, at an altitude of 7800 metres, "She could not resist any more. She stopped breathing right there," he said.
The Himalayan Times reported that Dr Strydom suffered from snow blindness followed by stroke.
Dr Gropel also had high altitude pulmonary oedema.
"He is of course hugely shattered. His wife has died and he was there at the time and he blames himself," Mrs Newman added.
His daughter-in-law's death was a huge shock.
"We know she reached an elevation of 8440 metres. She was just 400 metres shy of the summit," he said.
On Thursday, before the trip turned to disaster, Dr Gropel's Ivanhoe East Veterinary Hospital updated clients on Facebook saying the couple had reached Camp 4 after nine hours of "tough mountaineering".
They planned to rest for seven hours then attempt the summit.
"The area from Camp 4 is known as the death zone as the human body starts to deteriorate at that altitude, and oxygen tanks are required.
"There is only a small summit window due to an approaching cyclone.
"They will set out approximately 10pm local time and will have to contend with darkness, lack of oxygen, the infamous Hillary step and a race against time."
They had climbed in winds of up to 100km/h after delays in their departure due to snow storms.
The Melbourne woman was agonisingly close to the mountain's summit when she was forced back by altitude sickness. Photo / Facebook
Another climber in their group, Dutchman Eric Arnold, 35, also died up the mountain after suffering from high altitude sickness.
They are the first fatalities on Everest since expeditions resumed this year after last year's earthquake caused an avalanche that killed 19 people at base camp.
Foreign Minister Julie Bishop said consular assistance is being provided to both families.
"It is a difficult and challenging climb and many people have died," Ms Bishop told reporters today.
"We certainly extend our condolences to the family and loved ones of Marisa." Ms Bishop said the Australian government carried warnings about the risks of travelling overseas on its Smart Traveller website. "Undertaking adventures like climbing Mt Everest has additional risks," she said.
