Also, does your mum have any half siblings… same mum but father being the man she was married to.? If one of them also takes an Ancestry DNA test, it’s easier to compare and sort out, check and make a list of them. Anything else that doesn’t match with her sibling(s) are potentially your mums paternal relatives.
In Ancestry, look at the top 5 matches that have trees… see if you recognise the names. If you do, you can add a note or colour code them as a maternal match. Ones you don’t recognise, also make a note as possible paternal match. Check how many cM they match.
You can also search the results for surname matches and open their trees and search for the home person. Sadly there are many trees which have minimal or only living people in them so you can’t see any names. If it’s a very close match, try messaging them, say you match but not sure of the connection? Don’t reveal too much as they may not want to reply!
You can ask as many questions here.
Then move on to the next 5 matches, remember the smaller the cM number the more distantly related they are!