The best way to proceed depends on the answers you provide and many others things. The motion needs to be answered correctly.
You might find as the most basic of help my Legal Guide helpful What is a Summary Judgment?
Contact a lawyer in your area to give you some help. We cannot see documents online so no further observation is possible.
Good luck to you, and God bless.
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Based on the tenor of your question, it appears the case is in court. If your health insurance is through a benefit plan at work, it is covered under ERISA. Under ERISA you have to exhaust the administrative remedies set out in the Plan Description. Once the administrative remedies are exahusted, the matter can be filed in court.
Summary judgment is a pleading where the moving party asks the court to rule on the case as a matter of law. Typically, the moving party will say that "there are no genuine issues of material fact" and the court can rule on the matter as a matter of law. In other words there are no factual issues in the case.
You did not provide the basis for the defense lawyers motion. Your state's rules of civil procedure will set forth specific things that can be filed in opposition to the motion.