Central defender Musonda (pictured), 20, joins on a month`s loan from SkyBet League Two high-flyers Luton Town.
The Bedfordshire-born youngster has previously captained the Hatters' under-18 side, breaking into the first-team in 2016 before enjoying a brief spell with Braintree Town in the National League.
Standing tall at 6ft, his maiden goal for his parent club came in the EFL Trophy, heading home in the 10th minute as a youthful side defeated opposition from the league above in the shape of Gillingham.
Striker Nombe, 19, joins on loan from League One MK Dons for the rest of the season.
Another graduate of his parent club's academy, the forward has begun breaking into the first-team this season with substitute appearances in both the league and cups.
Of his two new signings, the City boss told the club`s official Pitchero website: “I feel that we did need to improve at both ends of the pitch, so we've brought in Frankie Musonda as a defender and Sam Nombe as a striker.
“They're both professionals who have been in and around their first-teams. Frankie has got good leadership qualities and good character; Sam has good pace, good power, and his previous manager at MK Dons included him in his senior squad.
“We believe they will come in and give us a real boost which sometimes you need. As much as you want to work with the players, communicate, and engage with them a couple of fresh faces at the right time can give everyone a lift so we're delighted with the two signings.”
As part of this squad re-shuffle, defenders Cristian Navarro and Matt Peake-Pijnen have departed the club.
Navarro has made a number of appearances this season at both left-back and centre-back, covering for injuries and suspensions for Freddie Grant and Lee Henderson respectively, including an appearance in the Emirates FA Cup Second Round at Notts County.
Peake-Pijnen, meanwhile, departs having made only one appearance off the bench.
Jonas said it was a tough decision to let them go: "Unfortunately, we have had to let a couple of players go to make sure that we balance the books. Cristian Navarro and Matt Peake-Pijnen have left the club, we really thank them for their work. Cristian has played a big part for us this season, he's a cracking lad, but I felt we needed to change a couple of things.
“Peakey again is a good lad but we will struggle to give him the gametime he needs: as a young player he needs to be playing week in, week out in order to improve and realistically we can't give him that”.