As noted above, check with her doctor.
One needs to make sure that a DNR order is done right, and that all state laws are obeyed. If the proper regulations & processes are not observed, a DNR order will not be honored by many health professionals.
For example: In Wisconsin, a patient must be certified to be a qualified patient by two physicians, one of whom is the attending doctor. Among other things, a qualified patient is one who is expected to die within 6 months, or one who has a condition which would make attempts at resuscitation futile, or cruel.
Then, the patient (or the patient’s Medical Power of Attorney or Guardian if the patient is not competent) must sign.
And then the signature must be witnessed by two disinterested parties, who also sign the proper forms.