Marylee... People sometimes feel embarrassed about using oxygen in public, because it can make noise, is cumbersome and invites questions and perhaps pity (or scorn). It could also be that your mom doesn't feel she needs it. Is she experiencing shortness of breath when out and about? I suspect that if she is, it isn't too severe or she would probably invite relief. It's no fun to gasp for breath.

As far as respiratory therapy, perhaps you can strike a deal with her just for a consult and then tell her the final decision is up to  her, once she hears what the therapist has to say and sees what s/he can do. Or get the doctor to tell her to go; at her age, she's likely to view the doctor as an authority figure to be listened to.

Good luck!

Kathi