hello.i read through the query and understand the concern regarding burns to the face that happened to your mother.
please understand burns scar or accidental scars will take a longer time to heal,i would recommend common treatment methods and remedies which are often effective in such scenarios.
first of all,proper nutrition and proper hydration is essential.Moisturising is essential for maintaining the elasticity and suppleness of the skin.
like mederma and bio-oil are usually effective and can be used.another treatment is usually using vitamin E
cream in combination with a cortisone
ointment in mild concentration to be applied topically and a multivitamin
tablet orally to speed up the healing process.
Natural remedies like turmeric,papaya,lemon juice etc can also be tried;efficacy varies from person to person and across skin types and degree of burns
if the burns are extensive,i would suggest to go consult a cosmetologist/plastic surgeon to explore all viable options in addition to the above
Hope the information helps and clarifies your doubts.take care and good day