You think it should be a mortal sin for a few elderly people to exchange greetings and a few life updates with each other in the Presence of the Lord Jesus? You want them to go to hell for chatting?
I don’t know how old you are, but elderly people (and even people in their 60s like me) are very aware of their own mortality and impending death. Just last night, I had a call from my childhood friend that her husband, in his early 60s, died of a massive heart attack (even though he was thin, active, not addicted to anything, and lived a healthy life.)
This awareness of mortality makes us more likely to reach out to those we love and friends we care for because we’re not certain we’ll see them again on this earth.
Also, many older folks communicate through face-to-face talking, not on a phone screen or a computer.
I agree with you that they should wait until they are in the narthex or lobby (or at this time of year, outside) before carrying on a conversation. But a greeting, an inquiry about health or circumstances, a sharing of a happy life incident (e.g., my daughter had her baby last night!)–that’s not deserving of hellfire.
These people who sometimes aren’t aware that they are talking loudly, probably because of age-related hearing loss, are your neighbors. Remember what Our Lord told us about our neighbors?
I sympathize with you trying to find absolutely quiet before and after Mass, but it’s probably unrealistic. Perhaps if you sit way up front in your nave, it will be quieter for you and less distracting. And I suggest trying to develop a mindset where you think the best of everyone rather than resenting them for interfering with your life. Humans have a way of not doing what we want them to do, and it’s best to just accept people and pray for the ones who are most irritating to you.
Hope this will help you out a little.