It seems that it was at least two of the artist, who signed "F. Morelli". Both - quite prolific: their pictures are common in the network. But the little-known, as other information about them except for "Italian, 19/20 cent." not available. By signature on your picture (see 1, 1) is best suited signature 1.2. It coincides not 100%but (another mark of the letter "r"), but the signature of this artist was not very stable (see 1.3). This Morelli painted mostly genre scenes from the life of the Italian common people (see 2 and 3), his paintings on religious themes, I have not come across.
Signature of 1.4, likely had another "F. Morelli": it is very different, and even wrote the artist is not oil, and watercolor views of cities of the Arab countries (see 4). The names of the same picture he gave in English.
The website
http://www.findartinfo.com/search/li...ame=F._Morelli there prices on the work of F. Morelli. But I think there both of these artists have for one and the same. However, it is possible that the way it is.
Here's this information about "F. Morelli".
By the way, Madonna on your picture can hardly be called "the Sistine" because copyist omitted available on the original image of Raphael's Pope Sixtus II (as well as the St. Varvara).