I'm sorry for the loss of your 10-year-old cat, and I appreciate your questions about adopting a new kitten. The decision to get a new pet after an older fur-friend has passed away is a deeply personal one, and I can't offer specific advice on what to do in your situation. Here are some things to think about though, in making your decision about whether or not you should get a new cat to keep your surviving cat company.
Will you have time to care for a new kitten, and make sure that your other cat will be able to interact with it safely?
Does your cat respond well to change?
Is your cat in good health? A cat who is sick or stressed won't likely respond well to a new cat, or any new pet.
Is there a way to help your cat deal with the loss of her feline friend that doesn't involve getting a new cat? For example, would extra playtime, attention and mental stimulation help her deal with her feelings of sadness?
Are the other members of your family ready to adopt a new cat? It's important that everyone in your household has been able to grieve the loss of your older cat too. Perhaps talk to other family members and see if they're ready for the responsibility that comes with bringing home a new cat.
Have you considered adopting a mature cat as a companion for your two-year-old cat?
As you can see, there are many things to think about before adopting a new cat as a companion for your remaining cat. It's clear that you care deeply about your kitty and I know that love and affection will help guide you in making the best decision for you, your cat, and your family. I wish you all the best in whatever you decide to do.