Could we be covid?

So my dad works as a security and he said the person he was working with last night said that he was together with a positive case 2 nights before. So he is now under isolarion at home for 14 days BUT, my mum and dad came to my door ( well my dad stood back) but my mum this morning came in full contact with me and my 2 kids and then tell me that they came in contact with someone that could be covid........ They didnt come in they stood outside for 10 minutes and left. Now Im constantly arguing with my husband, but I had no absolute idea that they were coming. What are my chances? And how can I tell them in a nice way not to come for some time? I feel completely lost right now at the fact that my 2 kids came in full contact with my mum 🤦‍♀️😏