My mum got bitten on the eye by a mosquito last night. the eye lid is now red and really swollen and she can barely open her eye. solutions please? :)

Antihistamine: Try taking antihistamine up to every 6 hrs when needed. If problem persists or worsen, see your doctor

See a doctor: See a doctor. If she rubs a mosquito onto the conjunctiva, she can get a localized anaphylactic allergic reaction that needs topical epinephrine and topical and/or oral steroids. If not, the eyelid inflammation is not what you typically see with mosquito bite, so consideration should be given to a pre-septal cellulitis crossing into the orbit from the sinuses which may need oral or IV antibiotic