It is not unusual for dogs to experience depression after the loss of a friend. Sometimes they are able to move on and sometimes they get stuck in a state of depression. Often the introduction of a new friend can help them to get a new leash on life.
If you are particularly interested in a Samoyed you would be best to thoroughly research the breed. Find out about their needs, how trainable they are, their downfalls (every breed has some), and in this case, grooming requirements. Your mother may be more willing to consider if she sees how serious you are.
Or,...you may decide that you really like the breed but it is not realistic for you to have one. It's okay to choose something else that fits your lifestyle and that of your family a little bit better. I love Borzois but I am terribly allergic to them, so I admire them from afar.
Hope this helps.
Zena & Zippy