She has read the four other letters but desperately wants to read the remaining two.
Monica, who lives in Australia, said her daughter suffered from depression.
"Show the others the letters I wrote other people too okay, especially my mum," Niki wrote in one of the six letters, addressed to her boyfriend.
"Let them read everything I wrote in my last days before they get to keep theirs."
But before that could happen police took the letters as part of their inquiry.
Monica said their content was not as important to her as fulfilling her daughter's last request because of their Hindu religion, which dictacted that a deceased person's final instructions must be carried out before their ashes could be put to rest.
She was breaking custom by keeping Niki's ashes at home, something she found deeply traumatising, and was exasperated by the system.
"I beg for your compassion and understanding as a grieving mother ..." Monica wrote to the two staff members on March 21.
"Nothing is going to bring my daughter back. I want to live my life fulfilling all of my Niki's wishes and dreams. Please allow me to do that. Please allow me to read her letters."
When there was no response to her plea, Monica sent a second request in April, this time copying in dozens of staff - some of whom she thanked for their support of her daughter before the 24-year-old's death.
"A human life has been lost, a life with a promising future ahead, a beloved child - I hope you will find it in your hearts to dignify my irreparable loss with some compassion and respect Niki's last wishes," Monica wrote.
In a response two days later, the university proctor said: "The letters cannot be released to you. Police continue to hold the letters as part of the coronial process."
Monica then wrote to the coroner's office asking for the release of the letters, receiving this response from a spokeswoman:
"[The coroner] advised that whilst she understands your desire to receive the notes, they are part of an ongoing coronial inquiry so she is not prepared to release them at this stage."
Desperate, Monica engaged lawyer Shaurya Malaviya who wrote to a police inquest officer on May 2, seeking the letters.
"I am sure you can understand the distress the Soni family is experiencing and this is being exacerbated by the fact that they are not able to fulfil Niki's last wishes."
He argued it would be very rare for a coroner to release relevant material in the lead-up to an inquest. The solicitor pointed to paragraph 9 of a practice note issued by the chief coroner.
"The coroner will provide copies of documents received in the course of the inquiry which are relevant to the issues to be addressed at the inquest to the immediate family and other interested parties upon request."
In response, he advised that the coroner was on holiday for two weeks.
The Herald approached the coroner's office at the weekend about the case. A coronial services spokeswoman said typically a family member was allowed access to information in a loved one's file before an inquest by making an application for it.
A university spokeswoman said it was unable to comment as the case was still before the coroner.
Monica told the Herald she could not put Niki's soul to rest until she read the letters.
"It has already been 78 days since Niki's passing. I would compare this to a Christian having to hold onto the body and not being able to bury it for this long.
"I'm being prevented from fulfilling my daughter's last wishes and to put her to rest. So it is traumatic for me to live with this every day. It is just impossible to move on."
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 or text HELP to 4357 (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757