Flanked by daughter Misa Bharti, son-in-law Shailesh and party MLA and national general secretary Bhola Yadav, the RJD supremo came out of the airport on a wheelchair and was received by a large number of supporters.
Later, Bhola Yadav told reporters that Mr Prasad had gone to Mumbai on May 22.
"Doctors said his haemoglobin level is low and he should undergo a surgery within two weeks, for an infection," he said.
Serving sentences in a number of fodder scam cases, Mr Prasad is currently out on provisional bail granted by the Jharkhand High Court for medical treatment.
"The six-week period for which provisional bail has been granted is not enough. We hope that he will soon be granted a regular bail so that he may regain his health without any worries," Mr Mehta said.
Asked whether the party leaders were missing him on account of restrictions imposed by the court, Mr Mehta said "There is a bit of disappointment though our leader's aura is immense. His mere physical presence is enough to electrify the cadres."