Yes. It is possible. I was allergic to my glasses whose frame is made of metal. So I had to exchange for plastic glasses frames. You'd better take your mother back to the optician to have a check. If it is caused by the metal glasses, then you should choose other types of material for your mother's glasses.
It is possible for some people to be allergic to the metal glasses frame. In this case, your mother should avoid metal glasses. She can switch to regular plastic frames. Or she can also get titanium or stainless steel eyeglasses which is hypoallergenic.