Giving Power of attorney from abroad (PoA)

Dear Sir, my cousin and his wife along with their two daughters visited the US in 2018 and received green card in 2021. Suddenly he passed away this month (March 3rd). As he used to maintain everything, his sudden demise has led her down a blind alley. She is in the want of money and cannot immediately visit India. She needs to sell of an apartment where they used to stay in Kolkata. Can she appoint anybody who can sell that apartment on her behalf in Kolkata? What will be the procedure please? Please guide.