Does bitcoin core 0.18 support bip44,bip39 (HD wallet) I am new to bitcoin. Struggling to implement HD wallet. goggled for the same but did not get satisfied answer. Can we create multiple seed in single bitcoin core server?

If yes, then how we can manage the private key of each generated seed.
   If no, then how we can create custom derivation path.  

Note: I am using json-rpc protocol to communicate with bitcoin core.
You seem to have confused a couple of things.

Firstly, HD wallets is specified by BIP 32, not BIPs 39 or 44.

Secondly, being able to set your own seed is completely unrelated to setting a custom derivation path. They are two different things that have no effect on each other.

Note that BIP 39 specifies a menmonic scheme, not a seed. When I say mnemonic, I will be referring to BIP 39 mnemonics. When I say seed, I refer to BIP 32 seeds. They are two different things.



Bitcoin Core has had BIP 32 HD wallet support since 0.13. Since 0.17, it has had a sethdseed RPC which allows you to replace a wallet's BIP 32 seed with a custom one or a newly generated one. Note  that this does not allow you to have multiple active seeds in one wallet.

While you can set a HD seed with sethdseed, you cannot set a BIP 39 mnemonic. BIP 39 mnemonics and the seeds that they produce are incompatible with Bitcoin Core.

Lastly, while you can set a new HD seed, you cannot change the derivation paths that are used to derive keys. Bitcoin Core does not follow BIP 44's derivation path specification. Instead it uses m/0'/0'/i' as the derivation path for receiving addresses, and m/0'/1'/i' for change addresses.