Here's what I found about Mauhur (source:
http://www.tuckborough.net/ )
'Mauhúr
Orc of Isengard. Mauhur may have been an Uruk-hai. On the night of February 28-29, 3019, Mauhur led a company of reinforcements through the eaves of Fangorn Forest to come to the aid of Ugluk. Ugluk's company had been surrounded by a group of Rohirrim led by Eomer. When Mauhur's company attacked, some of the Rohirrim rode to meet them while the others closed in around Ugluk's camp. Ugluk's captives Merry Brandybuck and Pippin Took found themselves outside the circle and were able to escape into Fangorn Forest. Mauhur and his company were killed or driven off by the Rohirrim.'
now about Ugluk:
'The Riders of Rohan surrounded Ugluk's company on a hillock near Fangorn Forest on the evening of February 28. Ugluk did not attack, for he believed that reinforcements led by Mauhur were coming. He ordered that Merry and Pippin were to be guarded and not slain unless the Riders broke through their defenses. Grishnakh disobeyed Ugluk and carried the Hobbits away to search them for the Ring, but he was slain by a Rider and Merry and Pippin were able to escape.
Mauhur's reinforcements arrived but they were defeated by the Rohirrim. At dawn on February 29, the Rohirrim attacked Ugluk's company. Ugluk managed to hold together a band of his followers and tried to escape into Fangorn, but they were eventually overtaken and killed. Ugluk fought Eomer, the leader of the Rohirrim, sword to sword but he was defeated and Eomer slew him.'
So it seems to me they both got killed :p
Hope this helped some of you.
Jorn.