Dear Binoj,
Your mother may try the following asanas that may help her from the chronic heart burn or acid reflux. Being senior citizen I would suggest to be more careful while doing postures and should be done within her capacity. I have given some instructions at slideshare reference for basics of asanas :
Though yogasanas can help to a certain extent, the more causative factor is lifestyle - state of mind when it is eaten (should be very peaceful), contents of the meals (try to be more alkaline), time and quantum (last meal should be over by 6:00 pm or evening) and the solid meal should fill the stomach by 50 per cent, remaining 25% by water and remaining 25% should be empty. The quantum may be reduced slightly.
Your mother should focus on chewing 30-35 times for each bite during meals. It really works wonder. Every meal may be followed by vajarasana (please be aware of the knees pain if she is suffering, then it can be avoided or if she has overweight issue).
If she is comfortable, you can consider shatkarmas - kunjal or dhauti kriya only under guidance of qualified yoga therapist. Jalaneti can also indirectly help her getting rid of acid issues.
You can also consider the article on the subject at the following link: https://www.healthline.com/nutrition/heartburn-acid-reflux-remedies#section13
You can feel free to write to me for further clarification. I will be happy to discuss further.
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