My condolences on your loss. Regardless of the circumstances, it is always difficult to lose a parent.

Do you know that if your mom's is a commercial plant, it is most likely to be a hybrid that won't come true from seed? However, there can be nice plants started from seed. There are some commonly available species such as sweet autumn clematis, so it is possible that it would come true from seed. First check that there are seeds in the center of the fuzzy seed heads. They are flattish and are attached to the long fuzzy tails that make up the cottony clusters.

If you are on Facebook, there is a clematis group (Crazy about clematis) where one avid clematis grower has been sharing photos of her clematis seed-starting operations. She soaks the seeds and then peels the outside seed coat. She puts them in covered plastic boxes on damp blotter paper, and then when the seeds start sprouting she moves them to starter cells with potting medium and grows them on under lights. If you plant them in a more usual fashion you may find that it takes anywhere from a year to 3 years for the seeds to sprout depending on the seed and conditions, so the blotter paper method seems to be much quicker.

Another way to start new plants that will be identical to the mother plant is to pin down some stems and leave them for a year - they will most probably grow roots and then can be separated from the mother plant. It is also possible to start clematis from cuttings, but I don't know much about it.