Legal Question in Family Law in California

Unfortunately for you, you probably do not have any rights in this matter.

Dead bodies are referred to in Health & Safety Code section 7001 as "human remains" or "remains." These remains are defined as the body of a deceased person, including the body in any state of decomposition as well as cremaed remains. (Health & Saf. Code, sect. 7001.)

There is a quasi-property right in the possession of a dead body, recognized for the limited purpose of determining who may have its custody for burial. (Sinai Temple v. Kaplan (1976) 54 Cal.App.3d 1103, 1110 fn. 13.) Custody of the remains may be determined by testamentary disposition. (Health & Saf. Code, sect. 7150 et seq.) (This means your mother's will.)

Alternatively, the decedent could have left directions in a health care directive or other written instrument pursuant to Health and Safety Code section 7100.1.

If the decedent has not left directions pursuant to Health & Safety Code section 7100.1, then the right to the control the disposition of the remains devolve on the next of kin, in the order set forth in Health & Safety Code section 7100 subdivision (a). You can read that list here:

http://www.leginfo.ca.gov/cgi-bin/displaycode?section=hsc&group=07001-08000&file=7100-7117

Unfortunately, the surviving spouse trumps the adult children in the hierarchy.