100% Fake.
1. Which son mutes his mic while on an actual video call with his mom? Even if he does, why would the mom keep talking when her son’s mic is muted?
2. The only messages in that chat are "Hi Amma" and some calls. Nothing else.
3. The lady has set a disappearing timer for that chat, which is suspicious and undermines the mother-son relationship.
4. The expression on the woman’s face upon seeing such content on her phone during the video call looks like she expected to see nudity, instead of being shocked or unexpected to see it, which she didn’t seem to do.
5. The guy is not pressured at all; he is confident in what he is doing, as if he is doing it for the right and intended person.
My suspicion is that she is some local prostitute, often referred to as "kanakamma" or "chellamma," where "amma" is also part of the name. Her younger clients usually refer to her as "amma" because she is older than them.