With the info you provide, it is impossible to say what is wrong with your mother's health.
Memory issues are often from the anesthesia during surgery. These effects normally subside, but that can take some time.
Blurry vision is often a side effect of medication.
It is still short after the surgery, so things will normally (slowly) further improve.
If there is instead of improvement, reason to believe that her condition is worsening, do not hesitate to contact the hospital for advice.