it is up to the Company if they wanted to pay to their staff leave salary with basic pay or along with allowances. This should be mentioned in the Contract singed by the employee and the employer.

Regarding ML, Company has a right to terminate the contract of the employee for a valid reason, but subject to notice period.
Company can ask the employee to work for the notice period or pay the employee notice pay and release with immediate effect.

Maternity leave has nothing to do with termination.

Check her contract and read the clauses carefully before taking any step against the Company.