Is it obligatory to prioritize aiding one's mother with Hajj over aiding one's paternal uncle with his medical treatment, in the event of being unable to do both?

God has placed the rights of parents in the second rank after His own rights, and He has favored the mother and given her precedence over the father. Therefore, you should enable your mother to perform Hajj, out of righteousness towards her and fulfillment of your promise. Then, if you are able to help your uncle, do so; and if you are not able, there is no blame upon you.