Can my mother's nursing home release her when she has open bedsores

The first thing to do is to document the bedsores. Take pictures of them and make sure the facility has been put on notice of them. 10NYCRR sec. 415.12 contains a list of required care and treatments that the nursing home "ensured" will happen relating to and including pressure sores.
In addition, NYCRR sec 415.12C(1) and (2) states that "the facility must ensure that 1. A resident who enters the facility whithout pressure sores does not develop pressure sores unless the individual's clinical condition demonstrates that they were unavoidable DESPITE EVERY REASONABLE EFFORT TO PREVENT THEM; and 2. A resident having pressure sores receives necessary treatment and services to promote healing, prevent infection and prevent new sores from developing.
If your mother can not walk, did the facility do everything possible to prevent bedsores such as wheelchair cushions, a special mattress, was she turned and re-positioned every few hours?
In light of the above, the facility should be treating the bedsores, not releasing her.
You may also have a potential lawsuit. It is recommended you speak with a personal injury attorney who can obtain and assess all of the facts of your mom's situation.