I don’t know where she lives, but does the family have access to hospice care? They can help the family through the process. My husband’s grandmother and the rest of the family were helped tremendously by hospice when she died. It is not a religiously oriented service, at least not as we experienced it, though they are certainly open to that I believe. The hospice personnel could help your aunt and her daughters examine their options.
hospicenet.org/ has a US, a UK and an International hospice directory on it.
In the US, one can have a memorial service at the funeral home that deals with the burial, if desired, which is what they did for my uncle who was not religious in any way. The funeral director can assist in planning a memorial service where friends and family have an opportunity to speak if desired. Most have a generic chapel sort of room that can be used. I’m sure they have some sort of option for music, either a piano, or a sound system for cds of music meaningful to her.
If she is dying of cancer, has she been asked what kind of funeral or memorial service she would like? It is not uncommon for terminally ill folks to want to be very involved in planning their own memorial services. It is an option for control that is not available obviously when someone dies suddenly. It may help to bring her some peace, knowing she has done what she could to ease the decisions that will be faced by her children and family after she is gone.