Sorry about your loss. That is a very pretty cabinet. You don't see many with the leaf to the edge of the drawers. I personally do not care for the paint job, but it does bring out the details.
I think that it is probably is from the very early 1900's. There is a very similar machine at
Need help identifying Sears Minnesota treadle sewing machine Just the first two posts - as the rest seem to be for different models.
Something a little different about this machine is that in order to remove the work from the machine, one needs to press the spoon shape thing under the tension dial. The manual in the second post of the above link/thread tells about it on page 6 of the pdf. I was just looking at a manual for a Singer 27 which has the same type of release, but it says to use the right thumb, rather than the left thumb to release the tension.
Janey - Neat people never make the exciting discoveries I do.