As a Danish citizen and dependent of how long time she have been living in Denmark and her age she may well be able to get the Danish old age pension. Dependent of the year she was born the age for starting is from 65 to 68.
She can phone the Danish Government pension department "Udbetaling Danmark" on phone +4570 12 80 61 and get more information by informing them of her Danish citizen number Cpr. Nr., the number is stated in her passport.
The max. Danish old age pension when living in Thailand is this year DKK 6.547 (THB 32.000)when you have lived in Denmark 40 years, if less years it will be reduced.