Is my mother drinking a qt. of gin a week, plus beer & wine a volume of concern? Is this too much & a danger for her?

Most definitely! She sounds like she has an alcohol problem - not unusual in the older generation. Many people just cover it very well. I hope you can talk her into going to AA - you may have to start with counseling if she will do that but not go to AA. If she won't do either (or even if she does), I'd strongly suggest that you attend some Al-Anon meetings. People there will be coping with the same issue and will be a great support for you.
Good luck.
Carol