I have worked in an industry connected with death care for over 20 years. Call your local funeral directors and have them quote you a price for a "direct cremation.' Many funeral directors will view cremation as an inexpensive choice, and, therefore potential income loss for them.
There's lots to consider....does your mom still want a "service or viewing" with the body present? Service at a church? Or at the funeral home itself? Then you will still add costs of the funeral home services, flowers, limo, etc. etc. etc. Many cemeteries still have memorialization options for cremation including ground burial (lot cost, grave opening and closing), niche units were the urn is displayed in an area designed just for that, disposition in a bench designed to accept an urn, etc. There are SO many options !
If you are interested in immediate cremation and return of the cremains to you/your family, just shop the lowest price for a direct cremation, they will return the remains in (most likely) a cardboard container, in a bag. You can purchase a nicer urn on-line at many many websites or make O. yourself of ceramic!
If your mom chooses and requests that her ashes be scattered at a particular site (beach, mountains, back yard) check the local laws, because in many instances, you can't just go and pour them anywhere! (Of course, that only applies if someone sees you!) Good luck!