Senior co-worker tells me to "go home"?

Background:: In June 2013 my church one volunteer needed a break. So in August my mom volunteered me. so except for late August/early Sept 2013-until March 2020 I had been cleaning up the sanctuary. Now at some point (2016/17) the volunteer came back- I work Wednesdays, she does Thursdays. The only time I “call out” is if I’m sick, or if it’s bad weather/icy. if it’s bad weather I try to arrange to come in on Thursdays instead after my program (unless they tell that the other volunteer will do it).

Main story
It’s a Wednesday and I come in and for some other reason-the senior co-worker (who works on Thursdays) is there. My main boss (the sectary) been out since Dec for knee sugery. I show up on my work day and see the senior volunteer is there. I check in with the Wednesday replacement sectary and they tell me to start doing my normal job I showed up for.

I’m about half-done the church and the senior volunteer shows up in the sanctuary to start doing the job I’m about half-finished- and is really surprised to see me there. She basically tells me to “Go home” and HER story is that “they asked her to come in” and the replacement sectary said that Senior volunteer “came in because she was bored”.

Whichever case it is the Senior volunteer got the impress that because the “Senior volunteer was in” she got the impression somehow I wasn’t coming in.

P.S. I told my parents later and Dad said that because I got a little upset that if “it happens again in the future” him or Mom needs to “meddle”. I was like and like “don’t I need to deal with co-worker problems on my own?” And when I told Mom even later she agreed with me (I just can’t remember about what though)

P.S.S
When bulletins happen again at church. How could I deal with this kind of problem with a sort of “co-worker” without my parents meddling?