Wa`alykum as-Salamu wa Rahmatullahi wa Barakaatuh.
Wudu is necessary for making sujud al-sahw according to the majority of scholars. However, there are some scholars like Ibn Taymiyyah who hold the view that one may do it without wudu. He argues there is no compelling evidence for making it essential.
Based on the latter view, you may still offer sajdah without wudu; however, it would be recommended to make wudhu, if you can.
Having said this, I would also suggest it is an excellent practice to be in a state of wudu unless there are valid reasons for not keeping the wudu. The Prophet said, “Wudu is the weapon of the believer.” By keeping wudu, one can be in a state of dhikr always, which helps to keep the Devil away. I pray to Allah to honor us to be in a state of remembrance always.
Allah Almighty knows best.
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